Communication of Control Information Using Alert Flag and Version Number

ABSTRACT

To effectively and efficiently provide control information, a broadcast pointer channel (BPCH) may be used to identify the type and perhaps relative location of control information that is being provided in a given frame structure, such as a sub-frame, frame, or superframe. A sub-frame (or like framing entity, such a frame or superframe) may have a BPCH and a corresponding system control information segment in which control information may reside. The system control information segment may have any number of control information blocks, wherein each control information block that is present may correspond to a particular type of control information. The BPCH is used to identify the type of control information that is present in a corresponding system control information segment, and if needed or desired, the relative locations of the various control information.

PRIORITY CLAIM INFORMATION

This application is a continuation of U.S. patent application Ser. No.14/723,574, filed May 28, 2015, titled “Communication of ControlInformation Using Alert Flag and Version Number”, invented by Mo-HanFong et al., which is a continuation of U.S. patent application Ser. No.12/921,672, filed Sep. 9, 2010, titled “Methods for Control Signalingfor Wireless Systems”, invented by Mo-Han Fong et al., now U.S. Pat. No.9,247,531, which is a National Stage Entry of International ApplicationNo. PCT/IB2009/000476, filed Mar. 10, 2009, which claims the benefit ofpriority to U.S. Provisional Application No. 61/035,363, filed Mar. 10,2008. All of the above-identified Applications are hereby incorporatedby reference in their entireties as though fully and completely setforth herein.

FIELD OF THE DISCLOSURE

This disclosure relates to methods for control signaling for wirelesssystems.

BACKGROUND

In most wireless communication systems, one or more base stationsfacilitate wireless communications with any number of mobile stationsthrough a wireless interface. A significant amount of information mustbe exchanged between the base stations and the various mobile stationsto enable communications therebetween. This information is generallydefined as control information. An exemplary wireless communicationsystem is defined by the Institute of Electrical and ElectronicsEngineers (IEEE) 802.16 standards as set forth by the Broadband WirelessAccess Working Group for Wireless Metropolitan Area Networks (MAN). TheIEEE 802.16 standard is commonly referred to as WiMAX, which stands forWorldwide Interoperability for Microwave Access.

The system requirements for the IEEE 802.16 standard are set forth inthe IEEE 802.16m standards, and like many other wireless communicationsystems, much of the control information that is used for system access,the transmission and reception of traffic packets, and handovers fromone base station to the next, is often transmitted and retransmitted adnauseum, regardless of whether the mobile stations actually need toreceive the information. In many instances, the mobile stations are insleep or idle modes, or already have received and stored the controlinformation. As such, the excessive retransmission of controlinformation that is either not needed by the mobile stations or hasalready been received by the mobile stations significantly increasescontrol overhead, wastes communication resources, and harms powerefficiencies due to the mobile stations having to remain awake toreceive and process control information that is either not necessary oris already available.

Accordingly, there is a need for a technique to more efficientlydisseminate control information to mobile stations in wirelesscommunication environments, including those defined by the IEEE 802.16standards and others, in an effective and efficient manner. There is afurther need for a technique to ensure that the mobile stationsefficiently obtain control information as necessary while reducing theneed to receive and process control information that has already beenreceived or is not relevant for operation.

SUMMARY

To effectively and efficiently provide control information, a broadcastpointer channel (BPCH) may be used to identify the type and perhapsrelative location of control information that is being provided in agiven frame structure, such as a sub-frame, frame, or superframe. Asub-frame (or like framing entity, such a frame or superframe) may havea BPCH and a corresponding system control information segment in whichcontrol information may reside. The system control information segmentmay have any number of control information blocks, wherein each controlinformation block that is present may correspond to a particular type ofcontrol information. The BPCH is used to identify the type of controlinformation that is present in a corresponding system controlinformation segment, and if needed or desired, the relative locations ofthe various control information.

For example, the BPCH may include presence flags for the different typesof control information wherein the presence flags are set according tothe presence or absence of corresponding control information in thesystem control information segment. If the system control informationsegment for a frame includes certain control information incorresponding control information blocks, the BPCH may have flags thatcorrespond to this control information set to indicate the presence ofsuch information, while other flags that correspond to other types ofcontrol information are set to indicate the absence of other controlinformation types. The BPCH may also provide the location, length, orthe like of the corresponding control information blocks within thesystem control information segment, such that the mobile station candetermine the precise location of the control information in the systemcontrol information segment. Each control information block maycorrespond to a different type of control information or a group ofcontrol information types.

Mobile stations can quickly and efficiently determine what controlinformation is present in a sub-frame, whether the control informationthat is present is relevant, as well as the location of any or all ofthe control information in the sub-frame. As such, the mobile stationcan avoid decoding control information that is not relevant. Inpractice, this means that the mobile station can quickly assess the needto decode the remainder of a sub-frame or at least the portion of thesub-frame that relates to control information once it has determinedwhether the sub-frame contains relevant control information.

Those skilled in the art will appreciate the scope of the presentinvention and realize additional aspects thereof after reading thefollowing detailed description in association with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thisspecification illustrate several aspects of the invention, and togetherwith the description serve to explain the principles of the invention.

FIG. 1 is a block representation of a communication environmentaccording to one embodiment of the disclosure.

FIG. 2 is a block representation of a base station according to oneembodiment of the disclosure.

FIG. 3 is a block representation of a mobile station according to oneembodiment of the disclosure.

FIGS. 4A and 4B represent sub-frame configurations according to oneembodiment of the disclosure.

FIGS. 5A and 5B illustrate sub-frame configurations according to asecond embodiment of the disclosure.

FIGS. 6-8 are tables disclosing seven types of control information.

FIG. 9 illustrates the use of a “BPCH present flag” which indicates thepresence or absence of the Broadcast Pointer Channel (BPCH). The“present” case is illustrated.

FIG. 10 illustrates the use of a BPCH to decode system broadcastinformation.

FIG. 11 is a table showing Pros and Cons associated with one dimensional(with a channelization tree) and two dimensional resource allocation.

FIG. 12 is a table showing Pros and Cons associated with multicast andunicast control.

FIG. 13 is a table showing Pros and Cons associated with TDM versus FDMof control and data.

FIGS. 14 and 15 present an overview of a control channel framework.

FIG. 16 is a table showing the number of partitions and the partitioningof 10 available resources for each value of the combination index.

FIG. 17 is a table showing number of available resources versus maximumnumber of assignments using a 10 bit CI.

FIG. 18 is a table showing an example of a permutation index look-uptable for the case where there are 4 sub-bands.

FIG. 19 shows a diagram that is signaled with a combination index thatindicates how the N resources are divided into 5 partitions of lengthsn₀, n₁, n₂, n₃, n₄.

FIG. 20 shows an example of a downlink control and traffic segment.

FIG. 21 shows an example of a group assignment segment.

FIG. 22 shows an example of an uplink control segment.

FIG. 23 shows an example of a retransmission segment.

FIGS. 24 and 25 are Tables for control channel overhead comparison.

FIG. 26 shows an example of a Mapping of Physical to Logical

Resources for a Diversity Zone.

FIG. 27 illustrates one embodiment of a channelization procedure.

FIG. 28 illustrates an embodiment of an alternative channelizationprocedure.

FIG. 29 illustrates an example of power vs. logical frequency (BCU) forthree sectors.

FIG. 30A illustrates an option where each carrier has a separate controlchannel.

FIG. 30B illustrates an option where a single control channel is usedfor multiple bands.

FIG. 31 illustrates the use of sub-maps in a legacy 802.16e system.

FIG. 32 gives an example of a group assignment bitmap.

FIG. 33 illustrates an example of an assignment bitmap and asupplemental transmission information field (STIF).

FIG. 34 is a table illustrating an example of partition divisions,corresponding index numbers and corresponding bitfields.

FIG. 35 illustrates an example of an assignment bitmap and a pairing orsets combination index.

FIG. 36 is a table showing an example of user combinations,corresponding index numbers and corresponding bitfields.

FIG. 37 is a table showing assignment ordering examples, correspondingindex numbers and corresponding index bitfields.

FIG. 38 illustrates the multiplexing of unequal assignments.

FIG. 39 illustrates an example of persistent resource assignment.

FIG. 40 illustrates an example of a multicast control segment (MCCS)including a combination index (CI) and a resource availability bitmap(RAB).

FIG. 41 illustrates an example of a combination index (CI) includinggroup assignment messages (denoted G₁, G₂, G₃), an uplink controlsegment (UL CS) and unicast assignment messages (denoted U₂ and U₃).

FIG. 42 illustrates an example of a resources map-uplink controlsegment.

FIG. 43 is a table illustrating an assignment overhead comparison fordifferent numbers of users.

FIG. 44 shows a unicast message on Carrier 1, where the unicast messageindicates that data in contained in a third partition of Carrier 2.

DETAILED DESCRIPTION

The embodiments set forth below represent the necessary information toenable those skilled in the art to practice the invention and illustratethe best mode of practicing the invention. Upon reading the followingdescription in light of the accompanying drawings, those skilled in theart will understand the concepts of the invention and will recognizeapplications of these concepts not particularly addressed herein. Itshould be understood that these concepts and applications fall withinthe scope of the disclosure and the accompanying claims.

Prior to delving into the details of the present invention, an overviewof an exemplary communication environment in which the present inventionmay be employed is described. With particular reference to FIG. 1, aportion of a cellular network is depicted wherein a base stationcontroller (BSC) 10 serves a plurality of cells 12. Each cell 12represents the primary coverage area of a particular base station (BS)14 that is operating under the control of the BSC 10. The base stations14 are capable of facilitating bi-directional communications through anynumber of communication technologies with mobile stations (MS) 16 thatare within communication range of the base stations 14, and thus withina corresponding cell 12. Communications throughout the cellular networkmay support voice, data, and media communications.

With particular reference to FIG. 2, a base station 14 configuredaccording to one embodiment of the disclosure is illustrated. Notably,the base station 14 may support any type of wireless communicationtechnology, such as traditional cellular technologies employingorthogonal frequency division multiple access (OFDMA), code divisionmultiple access (CDMA), and time division multiple access (TDMA), andlocal wireless technologies. Although not limited thereto, the conceptsof the present invention are applicable to the IEEE 802.16 standards asset forth by the Broadband Wireless Access Working Group for WirelessMetropolitan Area Networks (MAN), and in particular to the SystemRequirements for the IEEE 802.16 standards as set forth in section theIEEE 802.16m. This family of standards is incorporated herein byreference in its entirety. Notably, the technology defined by the IEEE802.16 family of standards is often referred to as WiMAX (WorldwideInteroperability for Microwave Access).

Accordingly, the base station 14 may act as any wireless access pointthat supports wireless communications. The base station 14 willpreferably be able to support unicast, multicast, and broadcastcommunications and effect the requisite control signaling to enable andcontrol the same. The base station 14 generally includes a controlsystem 20, a baseband processor 22, transmit circuitry 24, receivecircuitry 26, one more antennas 28, and a network interface 30. Thereceive circuitry 26 receives radio frequency signals bearinginformation from one or more remote transmitters provided by mobilestations 16. Preferably, a low noise amplifier and a filter (not shown)cooperate to amplify and remove broadband interference from the signalfor processing. Downconversion and digitization circuitry (not shown)will then downconvert the filtered, received signal to an intermediateor baseband frequency signal, which is then digitized into one or moredigital streams.

The baseband processor 22 processes the digitized received signal toextract the information or data bits conveyed in the received signal.This processing typically comprises demodulation, decoding, and errorcorrection operations. As such, the baseband processor 22 is generallyimplemented in one or more digital signal processors (DSPs). Thereceived information is then sent toward the core network via thenetwork interface 30 or transmitted toward another mobile station 16serviced by the base station 14. The network interface 30 will typicallyinteract with the core network via the base station controller 10.

On the transmit side, the baseband processor 22 receives digitized data,which may represent voice, data, or control information, from thenetwork interface 30 under the control of the control system 20. Thebaseband processor encodes the data for transmission. The encoded datais output to the transmit circuitry 24, where it is used by a modulatorto modulate a carrier signal that is at a desired transmit frequency orfrequencies. A power amplifier (not shown) will amplify the modulatedcarrier signal to a level appropriate for transmission, and deliver themodulated carrier signal to one or more of the antennas 28 through amatching network.

With reference to FIG. 3, a mobile station 16 configured according toone embodiment of the disclosure is illustrated. The mobile station 16will support a communication technology that is compatible with the basestations 14. The mobile station 16 will include a control system 32, abaseband processor 34, transmit circuitry 36, receive circuitry 38, oneor more antennas 40, and user interface circuitry 42. The control system32 will have memory 44 for storing the requisite software and datarequired for operation. The receive circuitry 38 receives radiofrequency signals bearing information from one or more remotetransmitters provided by base stations 14. Preferably, a low noiseamplifier and a filter (not shown) cooperate to amplify and removebroadband interference from the signal for processing. Downconversionand digitization circuitry (not shown) will then downconvert thefiltered, received signal to an intermediate or baseband frequencysignal, which is then digitized into one or more digital streams. Thebaseband processor 34 processes the digitized received signal to extractthe information or data bits conveyed in the received signal. Thisprocessing typically comprises demodulation, decoding, and errorcorrection operations. The baseband processor 34 is generallyimplemented in one or more digital signal processors (DSPs).

For transmission, the baseband processor 34 receives digitized data,which may represent voice, data, media, or control information, from thecontrol system 32, which the baseband processor 34 encodes fortransmission. The encoded data is output to the transmit circuitry 36,where it is used by a modulator to modulate a carrier signal that is ata desired transmit frequency or frequencies. A power amplifier (notshown) will amplify the modulated carrier signal to a level appropriatefor transmission, and deliver the modulated carrier signal to the one ormore antennas 40 through a matching network. Various modulation andprocessing techniques available to those skilled in the art areapplicable to the present invention.

Disclosed herein are various techniques to enhance the control signalingthat necessarily occurs between the base stations 14 and the mobilestations 16 to support overall system operation. These techniques aloneor in combination may reduce control overhead, save power, reduceprocessing requirements in the mobile stations 16 and base stations 14,allow faster network entry, save network resources, or any combinationthereof. The control signaling allows the base stations 14 and themobile stations 16 to communicate with each other to exchange importantinformation and operational instructions, which are referred to ascontrol information. Since the base station 14 is generally in controlof communications, a large portion of the control information isdisseminated by the base stations 14 to the mobile stations 16. Thecontrol information may be used to control system access, thetransmission and reception of traffic packets, handovers, and the like.

Since the control information is varied in nature, different types ofcontrol information have different characteristics. For instance,different types of control information may vary in terms of frequency ofchange, whether it is unicast, multicast, or broadcast, how robust itneeds to be, its importance to system access, and the like. Accordingly,different types of control information can be treated differently. Thefollowing description categorizes various types of control information,and based on how the information is categorized, effects delivery of thecontrol information accordingly.

To provide perspective and highlight the inefficiencies of the currentstate of the art, reference is made to the scheduling control and systeminformation is currently provided in the IEEE 802.16e standard.According to the IEEE 802.16e standard, scheduling information is sentin MAP messages, while system information is sent in separate uplink ordownlink channels. In addition, neighboring base station information andpaging information are broadcast in yet separate messages. Much, if notmost, of this information is periodically retransmitted regardless ofwhether it actually needs to be. For example, some of the informationprovided in the MAP messages, such as space time coding information,ranging region information, and fast feedback ranging definitions, isnot necessarily dynamic and therefore could be sent less frequently toreduce overhead. Some of the information provided in the uplink anddownlink channels is static, and thus either does not need to beperiodically broadcast by the base stations 14 to the mobile stations 16that have already entered the network, or could be broadcast at muchreduced rates. Such static information may include base stationidentifiers, operator identifiers, subnet identifiers, and time divisionduplex ratios.

Some of the information provided in the uplink and downlink channels issemi-static, and thus either does not need to be periodically broadcastby the base stations 14 to the mobile stations 16 if the information hasnot changed, could be broadcast at much reduced rates, or could bebroadcast when the information changes. Such information may includeburst profiles and handover parameters. Similarly, information forneighboring base stations is generally semi-static and does not need tobe periodically broadcast to the mobile stations 16 that have alreadyentered the network, assuming the information has not changed. From theabove, one can see that the need to provide or update controlinformation varies. While some control information is constantlychanging, other control information may only change periodically, if atall.

As an example, control information can be categorized as beingrelatively static, semi-static, or dynamic. Static control informationis relatively fixed. Semi-static control information will change on aperiodic basis or in response to a defined event. Dynamic controlinformation is information that may change on a relatively continuousbasis.

Regardless of being static, semi-static, or dynamic, control informationis typically delivered at defined locations in a framing structurewherein certain information is provided somewhere in a frame or group offrames each time the frame or group of frames is transmitted. Whilecontinuously providing dynamic control information may be necessary,continuously retransmitting static and semi-static control informationthat has not changed since the last transmission is very inefficientfrom both a processing and resource perspective.

With the present invention different types of control information may besent at different times to increase efficiency. For example, controlsignaling overhead may be reduced by having the base station 14 transmitstatic system-wide information that provides essential physical layerconfiguration information that is needed by a mobile station 16 toperform initial system access procedures in response to the base station14 detecting that the mobile station 16 is attempting to enter thenetwork. This is in contrast to having the base station 14 transmittingsuch information in each frame or sub-frame regardless of network eventsor conditions. The physical layer configuration information is used bythe mobile station 16 to establish communications with the base station14 for network entry to the network supported by the base station 14.The base station 14 can transmit static system-wide information thatprovides machine access code (MAC) or other upper layer configurationinformation after the mobile station 16 performs initial system accessusing the physical layer configuration information. The upper layerconfiguration information is not needed for initial system access andcan be unicast to the appropriate mobile station 16 to further increaseoverall system efficiency.

In the above scenario, the base station 14 may broadcast uplink ranging(or random access) information for the mobile station 16 that isentering the network to use when initiating uplink ranging (or randomaccess) procedures. The mobile terminal 16 that is entering the networkwill receive the uplink ranging (or random access) information and useit to initiate the uplink ranging procedures required to gain entry tothe network, wherein the procedures entail uplink transmission based onthe uplink ranging or random access information as is known in the art.

In the IEEE 802.16m standard, the framing structure is as follows. Asuperframe includes four frames and is transmitted every 20milliseconds. Each frame has eight sub-frames and is transmitted everyfive milliseconds. Each sub-frame generally corresponds to five, six, orseven OFDM symbols.

What follows provides a breakdown of different types of controlinformation into seven different categories and an exemplary way ofcontrolling the dissemination of the control information based on thecorresponding categories. Delivery of the various types of controlinformation may be based on appropriate events, conditions, orscheduling criteria. For the following example, the IEEE 802.16m framingstructure is used; however, those skilled in the art will recognize theapplicability of these concepts to different types of framingstructures.

Type 1 control information is considered static and corresponds toessential system-wide physical layer information that is used by themobile station 16 for decoding downlink physical layer frames/sub-framesthat are received from the base station 14. Exemplary controlinformation includes bandwidth configuration information, CP sizes,multi-carrier configuration information, system time, time divisionduplex (TDD) ratio information, guard tones, and the like. Type 1control information generally includes static system-wide deploymentspecific parameters, which are required for fast initial access duringnetwork entry. Mobile stations 16 should be able to decode the type 1information after synchronization with the serving base station or basestations 14. The type 1 control information should be delivered withvery high reliability, and can be broadcast either periodically or inassociation with an initial ranging event. If broadcast periodically,the information should be carried in a fixed resource location within asuperframe. If broadcast in association with an initial ranging event,the presence or absence of the control information is signaled by abroadcast pointer channel (BPCH), which will be described in furtherdetail below.

Type 2 control information is considered pseudo-dynamic (or aggressivelysemi-static) and may change from one superframe to another, but may notchange from one sub-frame to another or even be provided in any orsub-frame of a superframe. The Type 2 information corresponds toessential sector-wide physical layer information that is used by themobile station 16 for decoding downlink physical layerframes/sub-frames. Type 2 information may include channelizationinformation, legacy and 802.16m resource partitioning information,sub-frame control configuration information, superframe configurationcontrol information, and the like. The channelization information mayrelate to the partitioning of diversity zones, localized zone andinformation, pilot structure and information, and the like. The type 2information may also contain initial ranging region or code informationthat allows the mobile stations 16 to facilitate fast initial accessprocedures as set forth in the IEEE 802.16 standards. Since the type 2control information is generally required for fast initial access duringnetwork entry and handover, the mobile station 16 should be able todecode this information after synchronization and receipt of the type 1information. As indicated, the type 1 information may likely change fromone superframe to another, and as such, should be broadcast periodicallyevery superframe in a fixed resource location within a superframe or atthe boundaries of superframes, wherein the fixed resource location isknown by the mobile stations 16. Like the type 1 information, the type 2information should be delivered with very high reliability.

Type 3 control information is considered static and corresponds tonon-physical layer system information, such as base station identifiers,operator identifiers, subnet identifiers, and the like. This controlinformation does not have to be periodically broadcast to the mobilestations 16 and can be unicast to the mobile stations 16 during initialnetwork entry procedures. Further, this information does not have to beprovided in a fixed resource location in a superframe, frame, orsub-frame.

Type 4 control information is semi-static physical layer or MAC layerconfiguration information such as handover parameters, power controlparameters, fast feedback region information, ranging regioninformation, and the like. The type 4 control information can change ina relatively slow fashion in the order of seconds, minutes, or hours asopposed to the dynamic control information that may be changing and needupdating in periods of less than 100 milliseconds. For mobile stations16 that are already entered in the network, there is no need tobroadcast the type 4 information in a frequent manner, assuming theinformation has not changed. The design of the control channel shouldsupport efficient power saving for sleep and idle modes for the mobilestation 16 while ensuring any changes in the system configuration arereceived by the mobile station 16 in a timely fashion. For mobilestations 16 that are performing initial network entry, the type 4information may be sent as a unicast message to each mobile station 16during network entry to expedite network entry, after the base station14 has already completed the initial ranging procedures with theparticular mobile station 16.

Type 5 control information relates to information of or related toneighboring base stations 14 with respect to the serving base station14. The type 5 information may include static information correspondingto the type 3 information or semi-static information corresponding tothe type 4 information. The type 5 control information may be broadcastperiodically or in response to an event. The type 5 control informationcould also be unicast to any mobile station 16 that wants to add aneighboring base station 14 to an active set of base stations 14 thatare currently serving the mobile station 16.

Type 6 control information is paging information that is semi-static andcan be event driven. Whether quick paging or regular paging information,Type 6 control information is generally not periodic and should bebroadcast whenever there are one or more mobile stations 16 to page,generally in association with at least one mobile station 16 enteringthe network.

Type 7 control information is dynamic and relates to downlink and uplinkresource allocation and traffic burst assignment information, such asMCS, multiple-input multiple output (MIMO) mode, user identifier,resource allocation and the like. The type 7 control information mayalso encompass acknowledgements (ACKs) and negative acknowledgments(NAKs) of uplink traffic as well as power control information for uplinktraffic. The type 7 control information may change every sub-frame andbe unicast to a mobile station 16 if the traffic burst is unicast ormulticast/broadcast to a group of mobile stations 16 if the traffic bustis multicast/broadcast. The resource location information for one ormore mobile stations 16 being served by the base station 14 may bemulticast to the group of mobile stations 16.

To effectively and efficiently provide control information, a broadcastpointer channel (BPCH) is used to identify the type and perhaps relativelocation of control information that is being provided in a given framestructure, such as a sub-frame, frame, or superframe. In operation, thebase station 14 will identify the control information to provide in eachsub-frame, generate the sub-frames, and transmit the sub-frames in asequential fashion. For example, assume that control informationcorresponding to any one or more control information types 1, 3, 4, 5,and 6 may be present in a sub-frame or superframe boundary in an IEEE802.16m frame structure. As such, type 3 and 4 control information maybe provided in a first sub-frame while type 1 control information may beprovided in a subsequent sub-frame, which may not include the type 3 and4 control information. In one configuration, type 2 and 7 information isnot identified by the BPCH.

A sub-frame (or like framing entity, such a frame or superframe) mayhave a BPCH and a corresponding system control information segment inwhich control information may reside. As described above, not everysub-frame needs have a BPCH and the control information provided in thesystem control information segment may vary. The system controlinformation segment may have any number of control information blocks,wherein each control information block that is present may correspond toa particular type of control information. The BPCH is used to identifythe type of control information that is present in a correspondingsystem control information segment, and if needed or desired, therelative locations of the different control information. For example,the BPCH may include presence flags for the different types of controlinformation wherein the presence flags are set according to the presenceor absence of corresponding control information in the system controlinformation segment. If the control information segment for a frameincludes type 3, 4, and 5 control information in corresponding controlinformation blocks, the BPCH may have flags that correspond to type 3,4, and 5 control information set to indicate the presence of suchinformation while other flags that correspond to other types of controlinformation are set to indicate the absence of other information types.The BPCH may also provide the location, length, or the like of thecorresponding control information blocks within the system controlinformation segment, such that the mobile station 16 can determine theprecise location of the control information in the system controlinformation segment. Each control information block may correspond to adifferent type of control information or a group of control informationtypes.

With this configuration, mobile stations 16 can quickly and efficientlydetermine what control information is present in a sub-frame, whetherthe control information that is present is relevant, as well as thelocation of any or all of the control information in the sub-frame. Assuch, the mobile station 16 can avoid decoding control information thatis not relevant. In practice, this means that the mobile station 16 canquickly assess the need to decode the remainder of a sub-frame or atleast the portion of the sub-frame that relates to control informationonce it has determined whether the sub-frame contains relevant controlinformation.

The ability to efficiently determine if relevant control information ispresent and relevant in a sub-frame is particularly beneficial when themobile station 16 is not active and resides in a sleep or idle mode.This may be accomplished by monitoring the BPCH. In these modes, themobile station 16 is not actively engage in supporting voice, data, ormedia communications, but will periodically wake to obtain or check forrelevant control information. If the BPCH in a sub-frame that is beingmonitored indicates that no control information is present or controlinformation is present, but not relevant to that particular mobilestation 16, the mobile station 16 can quickly return to the sleep oridle mode without the need to decode the rest of the sub-frame,including any control information that is present but not relevant aswell as any resource and allocation information (type 7 ) that may beprovided in other portions of the sub-frame. The sooner the mobilestation 16 can return to the sleep or idle modes, the more power isconserved.

When the BPCH in a sub-frame indicates that the control information ispresent and the mobile station 16 determines that the controlinformation that is present is relevant to that mobile station 16, themobile station 16 can decode the control information. In certainconfigurations, the mobile station 16 can selectively decode only thatcontrol information that is relevant, such that when a system controlinformation segment has both relevant and irrelevant controlinformation, the mobile station 16 can decode the relevant controlinformation without decoding the irrelevant control information as wellas any resource and allocation information (type 7) that may be providedin other portions of the sub-frame. By eliminating the need to decodeirrelevant control information, the mobile station 16 can further savepower. Again when different types of control information are present,whether in allocated control information blocks or otherwise, the BPCHmay provide sufficient information to let the mobile station 16determine the location of the relevant control information so as toavoid the need to decode the irrelevant control information. As such,the mobile station 16 can selectively decode all or a portion of anycontrol information that is present in a sub-frame based on the BPCH.Importantly, not all sub-frames need to have control information at allin the system control information segment, let alone control informationof a particular type.

As with control information, a BPCH may or may not be present in eachsub-frame. The following examples illustrate two configurations fordetecting the present of a BPCH. For the first configuration, referenceis made to FIGS. 4A and 4B. In this configuration, the sub-frameincludes a control segment, an optional BPCH segment, an optional systemcontrol information segment, and a traffic segment for traffic bursts.The control segment may contain information related to the partitioningof resources within the sub-frame for traffic bursts. The controlsegment may be of fixed length and location, which are known to themobile station 16. The control segment is encoded and modulated in aknown fashion. The traffic segment carries information definingallocation of resources for traffic bursts.

A BPCH presence flag is added to the control segment of the sub-frame toindicate the presence or absence of the BPCH and perhaps the type andlocation of control information, if any, that follows in the systemcontrol information segment. When present, the BPCH may be of fixedlength and location, which are known to the mobile station 16. The BPCHmay also be encoded and modulated in a known fashion. In operation, themobile station 16 will process a sub-frame as follows. First, the mobilestation 16 will decode the control segment and analyze the BPCH presenceflag to determine whether the sub-frame includes a BPCH. If the BPCHpresence flag (1) indicates that a BPCH is present in the sub-frame asin FIG. 4A, the mobile station 16 will decode and process the BPCH suchthat all control information or any relevant control information in thesystem control information segment can be decoded. Any relevant controlinformation is then used by the mobile station 16 as desired. Theremaining resources in the traffic segment are for traffic bursts andare partitioned based on information in the control segment. The mobilestation 16 will handle the traffic bursts in traditional fashion inlight of the control segment information.

If the presence flag (0) indicates that a BPCH is not present in thesub-frame as in FIG. 4B, the mobile station 16 will recognize that theBPCH and the associated system control information segment are notpresent in the sub-frame. The remaining resources in the traffic segmentare for traffic bursts and are partitioned based on information in thecontrol segment. The mobile station 16 will handle the traffic bursts intraditional fashion in light of the control segment information.

In the above configuration, a BPCH presence flag is provided in thecontrol segment to indicate whether a BPCH, and thus a system controlinformation segment, is present in the sub-frame. In the configurationof FIGS. 5A and 5B, no BPCH presence flag is employed. If the BPCH ispresent, it will be provided in a fixed location in the sub-frame andwill have a fixed length as well as being provided with a fixedmodulation and coding scheme (FIG. 5A). In operation, the mobile station16 will first attempt to decode a BPCH at the location in the sub-framewhere it expects to find the BPCH. If decoding is successful, theinformation provided in the BPCH will allow the mobile station 16 toidentify and decode all or the relevant control information that isprovided in the system control information segment, as described above.If the decoding is not successful, the mobile station 16 will determinethat the BPCH is not present, and as such, there is no controlinformation provided in the control segment (FIG. 5B). The mobilestation 16 will then proceed to decode the control segment and thetraffic bursts that are provided in the traffic segment of thesub-frame.

With semi-static control information, such as information types 4 and 5as well as perhaps type 2, the base station 14 may take steps to informthe mobile stations 16 as to when the control information changes toenable further power savings by avoiding the need for the mobilestations to decode control information that has not been changed orupdated. Control information, version information, and an action timefor the control information may be sent from the base station 14 to themobile stations 16 at the same or different times in the same ordifferent messages. As the control information is updated, a new versionnumber is assigned to the control information such that each version ofthe control information can be identified and tracked. The versionnumber is referred to herein as a system configuration change count(SCCC). The action time identifies when the configuration informationshould take effect or be in effect. In general, the control informationis downloaded by the mobile station 16 and implemented at the actiontime. Until the action time, the mobile station 16 will use the priorversion of the control information.

In one configuration, the mobile station 16 may store current controlinformation that is currently in effect as well as new controlinformation in the memory 44 of the control system 32 that will takeeffect in the future at the designated action time. As shown in FIG. 3,the current control information (CI (A)) has a first SCCC (SCCC (A))while the new control information (CI (B)) has a second SCCC (SCCC (B)),which is different from the first SCCC. Periodically and in a frequentmanner, the base station 14 may send the current SCCC to identify thecurrent control information that is in effect as well as a systemconfiguration change alert (SCCA) flag to indicate whether new controlinformation (that is different from the current control information) isbeing provided by the base station 14. Again, the new controlinformation is generally control information that is scheduled to takeplace in the future. For example, the SCCC and the SCCA flag may beprovided every superframe in the corresponding superframe configurationcontrol (type 2) information.

By detecting the current SCCC value being provided by the base station14, the mobile station 16 is aware of the current control informationthat should be in effect and in current use. Assuming the mobile station16 has received and stored the current control information, the mobilestation 16 will use the current control information until new controlinformation is downloaded and the action time for switching to the newcontrol information occurs. When the action time occurs, the new controlinformation will become the current control information. If the mobilestation 16 detects an SCCC value being provided by the base station 14that corresponds to control information that is different from thatbeing used, the mobile station 16 will either switch to the appropriatecontrol information, if such control information is available in thememory 44, or cease uplink transmissions to the base station 14 andattempt to decode the appropriate control information from the downlinktransmissions from the base station 14. Once the appropriate controlinformation is recovered, the mobile station 16 will resume uplinktransmissions to the base station 14.

By monitoring the SCCA flag, the mobile station 16 can determine whetherthe base station 14 is broadcasting new control information that willultimately be used in place of the current control information. If theSCCA flag indicates the new control information is being broadcast, themobile station 16 will try to decode the broadcast messages in thecurrent and subsequent sub-frames that include the control informationof interest until the new control information is successfully decodedand stored in the memory 44.

When operating in an active, or normal, mode, the mobile station 16 mayoperate as follows to support power saving efforts. The followingoperation assumes that the mobile station 16 is using the currentcontrol information, which corresponds to the current SCCC that iscurrently being provided by the base station 14. If the SCCA flagindicates that no new control information is being broadcast, the mobilestation 16 does not need to decode the corresponding control informationthat is being provided by the base station 14. If the SCCA flagindicates that new control information is being broadcast AND if themobile station 16 has previously successfully decoded the new controlinformation that is associated with the new SCCC, the mobile station 16does not need to decode the new control information that is beingprovided by the base station 14. As such, certain sub-frames or portionsthereof that include the new control information need not be decoded. Ifthe SCCA flag indicates that new control information is being broadcastAND if the mobile station 16 has not previously successfully decoded thenew control information that is associated with the new SCCC, the mobilestation 16 should decode the new control information that is beingprovided by the base station 14. Such decoding may entail decoding theBPCH to determine the presence and location of the desired controlinformation in the system control information segment. As such, certainsub-frames or portions thereof that provide the new control informationshould be decoded.

When operating in a sleep or idle mode, the mobile station 16 mayoperate as follows to support power saving efforts. The base station 14will periodically transmit control information. The mobile station 16will wake up periodically, with the period set by the base station 14,to attempt to decode the current SCCC and the SCCA flag being sent inthe corresponding control information. Preferably, the wake up timeswill coincide with the time when the SCCC and the SCCA flag is beingbroadcast by the base station 14.

If the mobile station 16 detects that the SCCC being broadcast isdifferent from the SCCC for the control information that the mobilestation 16 has stored, the mobile station 16 should wake up during thecurrent sub-frame and stay awake during subsequent sub-frames to obtainthe current control information that corresponds to the SCCC beingbroadcast by the base station 14. Such decoding may entail decoding theBPCH to determine the presence and location of the desired controlinformation in the system control information segment. Once the currentcontrol information is obtained, the mobile station 16 will implementthe current control information and either begin uplink transmissions orreturn to the sleep or idle mode.

Assuming that the mobile station 16 has and is using the current controlinformation based on the SCCC being broadcast by the base station 14,the following operation may be provided to enhance power saving duringsleep or idle modes. If the SCCA flag indicates that new controlinformation is being broadcast AND if the mobile station 16 has notpreviously successfully decoded the new control information that areassociated with the new SCCC, the mobile station 16 can awake during thecurrent sub-frame and stay awake until it has decoded the new controlinformation that is being provided by the base station 14. Again, suchdecoding may entail decoding the BPCH to determine the presence andlocation of the desired control information in the system controlinformation segment. If the SCCA flag indicates that no new controlinformation is being broadcast, the mobile station 16 does not need todecode the corresponding control information that is being provided bythe base station 14 and can return to the sleep or idle mode, assumingthe mobile station 16 is within a normal sleep window or pagingunavailable window, without decoding the subsequent sub-frames.

From the above, control information may be categorized and delivered atdifferent times depending on the characteristics of the controlinformation, the operating mode of the mobile station 16, and the like.The following provides a couple of examples for allowing a mobilestation 16 to gain entry to the network, and thus a particular basestation 14 to initiate traffic communications. The exemplary categoriesdescribed above are used. For the first example, assume that thesubstantially static type 1 information, which is defined as essentialsystem-wide physical layer information for decoding downlink physicallayer frames or sub-frames, is broadcast in response to an initialranging event that is triggered by actions to initiate communications bya mobile station 16 that is in range of the base station 14. Furtherassume that the presence or absence of type 1, 3, and 4 controlinformation is signaled by the BPCH and provided in the system controlinformation segment as described above. The type 2 information may bebroadcast in a fixed location every superframe.

Initially, the mobile station 16 will synchronize with thesynchronization channel or preamble that is being provided by the basestation 14. The mobile station 16 will decode available type 2 controlinformation and obtain the relevant ranging region information. Theranging region information is provided as control information by thebase station 14 and must be used by the mobile station 16 whenperforming uplink ranging procedures. Accordingly, the mobile station 16will use the ranging region information to perform the uplink rangingprocedures. The base station 14 will detect the uplink ranging attemptsbeing made by the mobile station 16 and will transmit the type 1 controlinformation. The mobile station 16 will decode the type 1 controlinformation. The mobile station 16 will continue its ranging procedures,and then obtain any available type 3 and type 4 control information,which may be unicast by the base station 14 to the mobile station 16.The type 3 and type 4 control information may be transmitted on thedownlink physical layer frames that are being provided to the mobilestation 16.

For the second example, assume that the substantially static type 1information is periodically broadcast to mobile stations 16 that are inrange of the base station 14. Further assume that the type 1 controlinformation is provided in a fixed resource location within a superframeand that the use of a BPCH is not necessary for the type 1 controlinformation. The BPCH may be used for the type 3 and 4 controlinformation. The type 2 information may be broadcast in a fixed locationevery superframe.

Initially, the mobile station 16 will synchronize with thesynchronization channel and preamble information being provided by thebase station 14. Once synchronized, the mobile station 16 will decodethe type 1 information from the fixed resource locations of a particularsuperframe, and then decode the type 2 control information, preferablyusing the BPCH. If the BPCH is used, the mobile station 16 will identifythe location of the type 2 control information in the system controlinformation segment of a sub-frame based on the BPCH, and then decodethe type 2 control information accordingly. The mobile station 16 maythen perform any uplink ranging procedures based on the ranginginformation provided in the type 2 control information. Once the uplinkranging is complete, the mobile station 16 may obtain the type 3 andtype 4 control information that is being unicast from the base station14 in downlink physical layer sub-frames. Again, the type 3 and type 4control information may be obtained through the use of the BPCH asdescribed above.

Certain concepts of the above configurations may be employed in amulti-carrier environment. Multi-carrier environments are those thatallow mobile stations 16 to simultaneously receive information that istransmitted on two or more different carriers. For example, a 10 MHzspectrum can be divided into two 5 MHz carriers in order tosimultaneously support mobile stations 16 with 5 MHz bandwidthcapability, as well as those with 10 MHz bandwidth capability. Mobilestations 16 that have a multi-carrier mode are able to receiveinformation simultaneously on both the 5 MHz carrier and the 10 MHzcarrier. Not all of the carriers need to redundantly carry controlinformation. For example, system-wide and sector-wide system informationis common to all carriers. As such, there is no need to transmit thebase station ID on all carriers, as the base station ID will stay thesame regardless of the carrier or carriers being used. Repeating thecontrol information over multiple carriers merely increases overhead.Accordingly, at least two carrier types may be defined: a primarycarrier and a secondary carrier. A primary carrier may carry thesynchronization channel (or preamble), all of the system information,neighboring base station information, paging information, and resourceallocation and control information, which generally correspond to all ofthe categories of control information described above. As such, theprimary carrier may be used to carry type 1 through type 7 controlinformation. The secondary carrier may only carry a subset of the systeminformation, such as the type 2 control information, which is related tosuperframe configuration on the secondary carrier, as well as theresource allocation and control information of each sub-frame withinthat carrier, such as the type 7 information. This type of carrier mayalso carry the synchronization channel (or preamble) information.Regardless of the configuration, the different primary and secondarycarriers need not carry the same control information.

In general, one or more carriers within the spectrum can be designatedas primary carriers, while one or more carriers within the spectrum maybe designated as secondary carriers. Mobile stations 16 that only havethe capability to transmit and receive on a single carrier at a time areassigned to the primary carrier. Wideband mobile stations 16 that arecapable of transmitting and receiving on multiple carriers at a time areassigned to one or more primary carriers as well as one or moresecondary carriers. Based on the allocations described above, the basestations 14 may provide system broadcast information, such as type 1through type 6 control information and resource allocation and controlinformation, such as the type 7 control information, over the primarycarriers. Superframe configuration information, such as the type 2control information, may be transmitted at a superframe boundary overthe secondary carriers. Accordingly, the wideband mobile stations 16will monitor the assigned primary carriers for the system controlinformation, as well as the resource allocation and control information,and monitor the secondary carriers for the superframe configuration.

Channel information, such as channel quality information (CQI) of one ormultiple carriers may be fed back over either one of the carriers,depending on how the base station 14 has instructed the mobile station16. When configured to feed back the CQI of a secondary carrier, themobile station 16 has to measure the channel qualities associated withthe respective carriers. For example, the CQI of the primary carriershould be quantified based on the preamble or pilot symbols received viathe primary carrier, whereas the CQI of the secondary carrier should bemeasured based on the preamble or pilot symbols received via thesecondary carrier.

Additional embodiments are disclosed in the following Appendices.

APPENDIX A 802.16M CONTROL FRAMEWORK Problem

The application proposes the different aspects of control signalingmechanism between BS and MS to support system operation including systemconfiguration, resource allocation/control, paging, MS network entry,power saving modes, multi-carrier operation. The proposed scheme allowsreduced control overhead, enables power saving reduces MS processingrequirements and enables MS fast network entry.

What Solutions have been Tried and Why They Didn't Work

Here is a list of current solutions and the issues:

(1) In existing systems such as WiMAX and UMB, some static systeminformation are periodically broadcast even though MSs already enteredthe network do not need to read these information again.

(2) The concept of a Guide Channel is known and has similar function asthe BPCH we propose here, i.e. a channel that indicates the presence ofcertain types of control information in a frame. However, the knownGuide Channel is present in every frame whereas in this application wepropose methods to allow BPCH to be present only when necessary, toreduce overhead.

(3) The concept of primary and secondary carriers are known. However,the detailed mapping for what control information is carried on primaryand secondary carriers are not given. In this application, we categorizedifferent types of control information and propose how to map them toprimary and secondary carriers. Load balancing scheme across multiplecarriers are known. These do not provide solution related to controlsignaling. A common layer 2/3 protocol is known that anchors multiplecarriers. The common layer 2/3 protocol performs resource management andother system management for all the carriers. No details controlsignaling scheme was proposed, which this application addresses.

(4) Existing systems such as WiMAX and UMB do not have an efficient andpower saving way for MS in different power saving modes to track whetherit has the up to date system information.

Specific Elements or Steps that Solved the Problem and How They Do It

To reduce the broadcast control signaling overhead, we propose the BS totransmit static system-wide information, only when the BS detects thatthere is MS attempting to enter the network. There are two general typesof static system wide information. One is essential physical layerconfiguration information that is needed for initial system access.Second is MAC/upper layer information that is not needed for initialsystem access. For the former, the BS has to broadcast the informationonce it detects that there is one or more MSs attempting network entry.For the latter, the BS unicasts the information the MS after the MS hasperformed initial system access.

In order for the BS to detect if there is one or more MSs attempting toenter the network, the BS broadcast the uplink ranging (or randomaccess) information periodically so that MS attempting network entry candecode such information and use it for transmitting uplink ranging(random access).

Since different types of control signaling, e.g. system configurationbroadcast paging, resource allocation/control, should be sent atdifferent periodicity and some are event driven (e.g. paging informationdoes not have to be sent if there is no MS to page), we propose tosignal the presence of a particular type of control information using aBroadcast Pointer Channel (BPCH). An MS only needs to decode the BPCH tofind out if it needs to decode subsequent control channels. This enablepower saving. To further reduce overhead BPCH may not be present inevery frame. We propose two options for

MS to detect whether BPCH is present or not. One option is MS performsblind detection on the presence of BPCH. Second option is the presenceof BPCH is indicated by a flag in the multicast control segment (MCCS),where MCCS is a segment that is already present in every frame for thepurpose of resource allocation/control.

As it is critical for MS to receive system configuration informationsent by the BS, we propose schemes to enable MS to track whether it hasthe most up to date system configuration information sent by the BS. Theschemes proposed also enable power saving of MS in normal mode, sleepmode and idle mode.

We propose the overall MS network entry procedure based on thecomponents listed above.

For the case of multi-carrier deployment a wideband MS can be instructedby the BS to monitor a subset of the carriers for control information,for power saving purpose, reduce processing requirements, as well asreduce system control signaling overhead. We propose primary andsecondary carriers which carry different types of control Information.

Introduction

This contribution presents the types of control information required for802.16m system operation including system access, transmission/receptionof traffic packets, handover etc.

Different types of control information has different characteristics interms of the frequency of change, broadcast or unicast, robustnessrequirement, importance to initial system access, etc. Therefore,different types of control information should be treated differently.

This contribution presents how each type of control information shouldbe transmitted by the BS and received by the MS. A description of the MSnetwork entry procedure as well as sleep mode operation are provided interms of how the MS obtains the necessary control Information for properoperation. The support of multi-carrier operation is also described interms of how MS monitors each carrier for the necessary controlinformation.

Control Information in Legacy 16e System

In 16e, scheduling control information is sent in MAPs, while systeminformation is sent in DCD/UCD. In addition, neighbor BS information andpaging information are sent on broadcast MAC messages.

Some of the information sent on MAPs are not necessary dynamic andtherefore can be sent in less frequent manner to reduce overhead. E.g.,STC zone switch IE, ranging region definition, fast feedback regiondefinition.

Some of the information in DCD/UCD are static system information, thusdoes not need to be periodically broadcast to MSs that have alreadyentered the network or broadcast with a relatively long period toimprove reliability. E.g., BS ID, operator ID, subnet ID, TDD ratio.

Some of the information in DCD/UCD are semi-static system configurationinformation, thus does not need to be periodically broadcast to MSs thathave already entered the network if the configuration hasn't beenchanged or broadcast with a relatively long period to improvereliability. E.g., burst profile, handover parameters.

Similarly, neighbor BS information which is semi-static information doesnot need to be periodically broadcast to MSs that have already enteredthe network if the configuration hasn't been changed.

FIGS. 6-8 present a table describing seven types of downlink (DL)control information.

Broadcast Pointer Channel (BPCH)

The broadcast of Information types (1), (3), (4), (5), (6) may or maynot be present in a sub-frame or superframe boundary. To efficientlyindicate the presence/absence of these information block, a 16mBroadcast Pointer Channel (BPCH) is introduced.

The 16m BPCH contains the following: information blocks presence flags;and length of each information block that is present.

Examples of information blocks are:

-   -   System information types (1), (3) (4) and (5). In this        information block, multiple MAC management messages for the        different information types can be encapsulated.    -   Paging information (type (6)) (either quick paging or full        paging information).

The benefit of 16m BPCH is to allow sleep mode and idle mode MS to onlydecode the 16m BPCH to find out if broadcast information is present andwhether the broadcast information present is relevant or not (e.g.paging information is not relevant to sleep mode MS).

-   -   If the broadcast information is not present or the broadcast        information not relevant, the MS can go back to sleep without        the need to decode the rest of the sub-frame and the resource        allocation/control information, i.e. type (7).    -   If the broadcast information is present and relevant, the MS        just needs to decode the relevant broadcast information and go        back to sleep without the need to decode the rest of the        sub-frame and the resource allocation/control information, i.e.        type (7).

BPCH may or may not be present in each sub-frame. There are two optionsof how the presence of BPCH can be detected.

Option 1: A ‘BPCH present’ flag is added to the multicast controlsegment (MCCS) to indicate the presence/absence of the BPCH, e.g., asillustrated in FIG. 9. Note that MCCS contains control information toindicate the partitioning of resource within a frame for traffic bursts.MCCS is of fixed length and modulation/coding (refer to contribution NNNfor details).

-   -   An MS first decodes the MCCS. If the ‘BPCH present’ flag is set        to ‘1’ (i.e. BPCH is present) the MS will decode the BPCH. The        length and modulation/coding of BPCH is fixed. The information        contained in BPCH will allow the MS to decode the system        broadcast information that follows. The remaining resource in        the sub-frame is for traffic burst and the partitioning of those        resource is signaled by the MCCS.    -   If the ‘BPCH present’ flag is set to ‘0’ (i.e. BPCH is not        present), the MS will know that both BPCH and system broadcast        information are not present. The remaining resource in the        sub-frame is for traffic bursts, and the partitioning of those        resource is signaled by the MCCS.

Option 2: If present, BPCH is located at fixed location in a sub-frame,e.g., as shown in FIG. 10. It has fixed length and modulation/coding. MSperforms blind detection to decide if BPCH is present or not.

-   -   An MS first attempts to decode BPCH. If decoding successful, the        information contained in BPCH will allow the MS to decode the        system broadcast information that follows. The remaining        resource in the sub-frame contains the MCCS and resource for        traffic bursts. The partitioning of the resource for traffic        burst is signaled by the MCCS. Note that MCCS is of fixed length        and modulation/coding.    -   If MS does not successfully decode the BPCH, the MS will assume        that both BPCH and the system broadcast information are not        present. The MS proceeds to decode the MCCS and the rest of        traffic burst if applicable.

Transmission of System Configuration Information (Type 4)

As this type of information is semi-static and can change, the BS has toinform the MS in a timely manner when the information changes whileenabling power saving of MS.

Here is the proposed approach:

(A) A ‘system configuration change count (SCCC)’ is included in thesystem configuration broadcast messages sent from the BS. It is used toindicate the version number of the associated system configurationinformation. An action timer is included in the systemconfiguration-broadcast messages to indicate when the associated systemconfiguration takes effect.

(B) Overall, an MS stores up to two sets of SCCC values andcorresponding system configuration information in its memory. One is theSCCC value and corresponding system configuration information currentlyin effect. The other is the SCCC value and corresponding systemconfiguration information that will take effect at a specific actiontime.

(C) BS transmits a SCCC and a ‘system configuration change alert (SCCA)’flag periodically in a frequent manner. For example, every superframe aspart of the superframe configuration control information, i.e. type (2).The SCCC is used to indicate the version number of the systemconfiguration information currently in effect. The SCCA flag is used toindicate if BS has broadcast new system configuration information thanthose associated with the current SCCC.

(D) By detecting the SCCC value, the MS knows the current version of thesystem configuration information in effect and therefore can configureitself accordingly if the MS has previously received the correspondingsystem configuration broadcast messages. By detecting the SCCA flag, theMS knows if BS has broadcast new system configuration information. Ifthe flag is set to ‘1’, the MS will try to decode the systemconfiguration broadcast messages in current and subsequent subframesuntil it has successfully decoded the information.

(E) If MS has detected an SCCC value from the BS that is different fromthe SCCC value(s) the MS has stored, the MS shall cease UL transmissionand attempt to decode system configuration broadcast messages from theBS in the downlink. The MS shall only resume UL transmission after ithas successfully decoded the system configuration broadcast messagesthat contain the SCCC value.

-   -   (F) To Support Power Saving for MS in Normal/Active Mode:    -   If MS has detected that SCCC value has not changed and SCCA flag        is set to ‘0’, the MS does not need to decode the system        configuration broadcast messages indicated in the BPCH.    -   If MS has detected that SCCC value has not changed and SCCA flag        is set to ‘1’ and if the MS has previously successfully decoded        the system configuration broadcast messages with new SCCC value,        the MS does not need to decode the system configuration        broadcast messages indicated by the BPCH.    -   If MS has detected that SCCC value has not changed and SCCA flag        is set to ‘1’ and if the MS has not previously successfully        decoded the system configuration broadcast messages with new        SCCC value, the MS has to decode the system configuration        broadcast messages indicated by the BPCH.    -   (G) To Support Power Saving for MS in Sleep Mode or Idle Mode:    -   BS periodically transmit the system broadcast information.    -   MS in sleep mode or idle mode wakes up periodically (with period        configured by the BS) to attempt to decode the SCCC/SCCA sent in        the superframe configuration control information. The wake-up        time of the MS should coincide with the time when the SCCC and        SCCA is broadcast by the BS.    -   If the MS detects that SCCC has changed and the value is not the        same as what it stores in the memory, the MS shall be awake in        this subframe and subsequent sub-frames to decode BPCH and the        system broadcast information until it has successfully decode        system configuration broadcast messages from the BS that        contains the SCCC value.    -   If the MS detects that SCCC has not changed but SCCA flag is set        to ‘1’ and the MS has not previously received system        configuration broadcast messages from BS that contains a new        SCCC value, the MS shall be awake in this subframe and        subsequent sub-frames to decode BPCH and the system broadcast        information until it has successfully decode system        configuration broadcast messages from the BS that contains a new        SCCC value.

If the MS detects that SCCC has not changed and SCCA flag is set to ‘0’,the MS can go back to sleep (if it is in sleep window or pagingunavailable interval) without the need to decode the subsequentsub-frames

Initial Network Entry Procedure at MS

There are two methods for MS network entry procedures which correspondto the two options for the type (1) shown in FIG. 6.

Method 1 Based on Option (1a) of Type (1) Information:

-   -   Step 1: MS synchronizes with sync channel/preamble.    -   Step 2: MS decodes information type (1).    -   Step 3: MS decodes information type (2).    -   Step 4: MS performs UL ranging procedure based on the ranging        region information given in information type (2).    -   Step 5: MS obtains type (3) and type (4) information through        unicast signaling from the BS, transmitted on DL PHY sub-frames.

Method 2 Based on Option (1b) of Type (1) Information:

-   -   Step 1: MS synchronizes with sync channel/preamble.    -   Step 2: MS decodes information type (2) and obtain the ranging        region information.    -   Step 3: MS performs UL ranging procedure based on the ranging        region information given in information type (2).    -   Step 4: BS detects the MS ranging attempt, and BS transmits the        information type (1). MS decodes the information type (1).    -   Step 5: MS continues the ranging procedure.    -   Step 6: MS obtains type (3) and type (4) information through        unicast signaling from the BS, transmitted on the DL PHY frames.

Multi-Carrier Support

In the case of contiguous spectrum, multi-carrier mode is used tosupport MSs with different bandwidth capability. For example, a 10 MHzspectrum can be divided into two 5 MHz carriers in order tosimultaneously support MSs with 5 MHz bandwidth capability and 10 MHzbandwidth capability.

Not all the carriers need to carry all the system broadcast information,as system-wide and sector-wide system Information are common to allcarriers. Repeating the information over multiple carriers increase theoverhead.

Two Types of Carriers can be Defined.

-   -   (A) Primary carrier: this is a carrier that carries the        synchronization channel (or preamble), all the system        information, neighbor BS information, paging information and        resource allocation/control information, i.e.,        information-type (1) to type (7) described in FIGS. 6-8.    -   (B) Secondary carrier: this is a carrier that carries a subset        of the system information, i.e., information type (2) for        information related to superframe configuration on that carrier;        as well as the resource allocation/control information of each        sub-frame within the carrier, i.e. type (7). This type of        carrier may also carry the synchronization channel (or        preamble).

One or multiple carriers within the spectrum can be designated asprimary carriers. One or multiple carriers within the spectrum can bedesignated as secondary carriers.

A narrowband MS, i.e. an MS that has bandwidth capability totransmit/receive on only one carrier at a time, is assigned to a primarycarrier.

A wideband MS, i.e., an MS that has bandwidth capability totransmit/receive on multiple carriers at a time, is assigned to one ormultiple primary carriers.

A wideband MS monitors only the assigned primary carrier(s) for systembroadcast information, i.e. type (1) to type (6), and resourceallocation/control information, i.e. type (7), for new traffic packettransmission. The wideband MS also monitors secondary carrier(s) forsuperframe configuration broadcast information, i.e. type (2) at thesuperframe boundary. The MS may monitor the resource allocation/controlinformation, i.e. type (7), on secondary carrier(s) for HARQretransmissions. Details of HARQ ACK/NAK and retransmission formulti-carrier operation is given in other appendices. A wideband MS maybe configured by the BS to feedback the channel quality information(CQI) of one or multiple carriers. When configured to feedback the CQIof a secondary carrier, the MS has to measure the channel on thecorresponding carrier through either the preamble or pilot signals senton that carrier.

Key Techniques

Method for BS to determine when to transmit the static system wideinformation for MS entering the network in an event-triggered manner.

Method for BS to transmit information related to uplink initial randomaccess or initial ranging resource to MS prior to MS entering thenetwork.

Method for BS to indicate the presence/absence of certain systembroadcast information.

Method for BS and MS to synchronize on the system configurationinformation

Method for MS to perform initial network entry.

Method to send various types of control information over multiplecarriers.

APPENDIX B: PROPOSAL FOR IEEE 802.16M RESOURCE ALLOCATION AND CONTROL

Document Number: IEEE C802.16m-08/176.

Date Submitted: 2008 Mar. 10.

Source: Sophie Vrzic, Mo-Han Fong, Robert Novak, Jun Yuan, Dongsheng Yu,Anna Tee, Sang-Youb Kim, Kathiravetpillai Sivanesan.

Nortel Networks.

Re: IEEE C802.16m-08/005-Call for Contributions on Project 802.16mSystem Description Document (SDD), on the topic of “Downlink ControlStructure”.

Purpose: Adopt the proposal into the IEEE 802.16m System DescriptionDocument.

Scope

This contribution presents the IEEE 802.16m resource allocation andcontrol design for single band operation.

The resource allocation and control design for multi-band operation ispresented in a separate section. (C802.16m-08_178 also included in otherappendices).

Background

The legacy 16e system uses a two dimensional approach to assignresources to users. This requires a lot of overhead in signaling theassigned resources.

Other systems such as LTE and UMB use a one dimensional approach basedon a channel tree to reduce the resource assignment signaling overhead.

-   -   Each assigned user is allocated resources by assigning a node        from the tree.    -   Although a channel tree can save in signaling overhead, there        are some restrictions in the number of base nodes that can be        assigned.    -   For example, if a binary tree is used then only 2, 4, 8, 16,        etc. nodes can be assigned. Also, if more granularity is added        to the tree the total number of nodes increases, which increases        the number of bits that are required to signal each assignment.

The legacy 16e system is also inefficient in power since it relies onbroadcasting and/or multicasting assignment information.

-   -   Both UMB and LTE systems have lower power overhead since the        assignment information is transmitted using separate unicast        messages, which are power controlled to the each user        individually.

The legacy 16e system uses a TDM approach for multiplexing control anddata within a subframe.

-   -   Since the assignment information is located in the same region        of the sub-frame in all sectors and since the information is a        multicast message, no power boosting can be applied.

FIG. 11 is a table showing Pros and Cons associated with one dimensional(with a channelization tree) and two dimensional resource allocation.

FIG. 12 is a table showing Pros and Cons associated with multicastcontrol and unicast control.

FIG. 13 is a table showing Pros and Cons associated with TDM versus FDMof control and data.

Requirements from SRD

System Overhead: Overhead, including overhead for control signaling aswell as overhead related to bearer data transfer, for all applicationsshall be reduced as far as feasible without compromising overallperformance and ensuring proper support of systems features.

Motivation

In order to improve the overhead of the control channel of the legacysystem and make it better than existing systems such as UMB, LTE, a newcontrol channel design is proposed for IEEE 802.16m sub-frames.

The control and traffic channels are confined within each sub-frame andspan across all the symbols within the sub-frame.

Extended sub-frames can be defined to concatenate the sub-channelresource across multiple sub-frames to reduce control overhead andimprove UL coverage. This is for FFS.

The control channel consists of a short multicast message and separateunicast messages for each assignment.

-   -   Multicast message is kept very small since it is power        controlled to the lowest geometry user that is assigned in the        given sub-frame.    -   Each unicast message is power controlled to the intended user.    -   Group assignments messages are used for VoIP. The contents of        the group assignment message is described in another section.        (C80216m-08_177 also included in other appendices).

The multicast message is a 10 bit message that is used to indicate howthe available resources are partitioned. The partitions are notassociated with any channelization tree so there is no restriction tothe number of resources that can be assigned to a mobile.

The multicast message also removes the need of signaling a node ID foreach assignment. This leads to a significant reduction in overhead sincemost channelization trees use 9-11 bits for signaling a node ID. Thereduction in overhead increases as the number of assignments increases.

Overview of Control Channel Framework

The bandwidth can be divided into one or more zones, which can be eitherdiversity zones or localized zones. Each zone consists of an integernumber of Basic Channel Units (BCUs) (see contribution C80216m-08_175also included in other appendices).

Separate control channels are defined within each zone to assignresources within the zone.

The multicast control segment plus other DL control channels (e.g.

HARQ ACKs, power control bits) consist of an integer multiple of BCUs.

A diversity zone can contain a persistent sub-zone and a non-persistentsub-zone. A localized zone contains only the non-persistent sub-zone.

The multicast control segment indicates how the available resources arepartitioned.

-   -   This includes unused resources in the persistent sub-zone as        well as the non-persistent sub-zone.    -   The multicast control segment for a diversity zone consists of a        combination index (CI) and if persistent resources are allocated        it consists of a resource availability bitmap (RAB) (see VoIP        contribution C80216m-08_177 also included in other appendices).    -   For a localized zone, the multicast control segment consists of        a permutation index (PI).

The multicast control segment is power controlled to the lowest geometryuser that is assigned within the sub-frame.

The multicast control segment sent in a diversity zone along with othermulticast and broadcast channels.

FIGS. 14 and 15 present an overview of a control channel framework.

Content of Multicast Control Segment for a Diversity Zone

The multicast control segment consists of a 10 bit combination index.

The index is an index to a look-up table that consists of all possiblecombinations of an ordered list of k partitions of size n₁, n₂, . . . ,n_(k), where Σn_(i)=N, i=1, 2, . . . , k. The partitions in each listare ordered in increasing size.

In order to reduce the size of the combination index, a fixed maximumnumber of assignments is assumed. The maximum number of assignmentsdepends on the number of available resources. If more assignments areneeded then a second combination index is used to further partition theresources.

FIG. 16 is a table showing the number of partitions and the partitioningof 10 available resources for each value of the combination index.

Combination Index Look-up Table

The combination index look-up table depends on the number of resourcesavailable.

The table below shows the number of users that can be assigned with onecombination index (10 bits) for a given number of available resources.

For bandwidths that contain more than 24 BCU, multiple combinationindices are used.

FIG. 17 is a table showing number of available resources versus maximumnumber of assignments using a 10 bit CI.

Example Using the Combination Index

For example, if there are a total of 24 BCUs and 4 mobiles are scheduledas follows:

-   -   MS 1: 6 units;    -   MS 2: 4 units;    -   MS 3: 10 units;    -   MS 4: 4 units.    -   The combination index corresponding to CI(4,4,6,10) is signaled        on the multicast control channel.

The maximum number of assignments with one combination index of 10 bitsis 8. If more than 8 assignments are needed then another combinationindex is used to partition the last partition in the previouscombination index.

For example, to assign 9 users with a combination index corresponding toCI(1,1,1,2,2,3,4,4,6), two combination indices can be used.

-   -   The first combination index corresponds to 8 partitions of 24        available resources CI₂₄(1,1,1,2,2,3,4,10).    -   The second combination index, which partitions the last        partition in the previous CI (10 resource units), corresponds to        CI₁₀(4,6).

Content of Multicast Control Segment for a Localized Zone

For localized channel assignments a permutation index (PI) can be usedinstead of a combination index to indicate the sub-bands assigned todifferent users.

The permutation index represents the number of contiguous sub-bands thatare assigned to each user. Non-contiguous sub-bands can be assigned to amobile with separate assignment messages.

The mobiles are assigned in order of their assigned sub-bands.

If the number of assignments is k and the total number of sub-bands isN₈ then permutation Index represents a vector (n₁, n2, •••, n_(k)),where Σn_(i)=N₈ and n_(i)>0, i=1, 2, . . . , k.

For example, if the permutation index represents the vector (n₁,n₂,n₃)then the first mobile is assigned the first n₁ sub-bands, the secondmobile is assigned the next n₂ sub-bands and the third mobile isassigned the next n₃ sub-bands.

If the number of sub-bands is 8 and the maximum number of assignments is8 then the number of permutations is 128 (7 bits).

In general, if there are N sub-bands with up to N assignments then thenumber of permutations is 2^(N−1) and therefore N-1 bits are requiredfor the permutation index.

Example Using the Permutation Index

The table in FIG. 18 shows an example of a permutation index look-uptable for the case where there are 4 sub-bands.

In this case, there are a total of 8 permutations and only 3 bits arerequired to signal the PI.

Non-Persistent Resource Assignment within a Diversity Zone

The ordered list of available resources within persistent andnon-persistent sub-zones are divided into several segments.

The segments are ordered in increasing partition size.

The Different Types of Segments Include:

-   -   An UL control segment;    -   DL Unicast control and traffic segment;    -   DL Retransmission control and traffic segment in the case        resource adaptive synchronous HARQ is used (for asynchronous,        this segment is not present since asynchronous HARQ        retransmission can be assigned by the unicast control and        traffic segment);    -   DL Group control and traffic segment.

The diagram in FIG. 19 is signaled with a combination index thatindicates how the N resources are divided into 5 partitions of lengthsn₀, n₁, n₂, n₃, n₄.

Unicast Control and Traffic Segment

The unicast control and traffic segment consists of one unicastassignment. There can be multiple unicast control and traffic segments.

The unicast message is scrambled by the user ID of the intended user.

The length of the message depends on the type of assignment. There are alimited number of message lengths (e.g. 2). The mobiles use blinddetection to decode the message.

Each unicast message is followed by the data for the intended user.

The length of the unicast message can be a fraction of a BCU.

FIG. 20 shows an example of a downlink control and traffic segment.

Group Control and Traffic Segment

The group control and traffic segment is used for real time traffic suchas VoIP. There can be multiple group assignment segments (see VoIPcontribution C80216m-08_177 for details also included in otherappendices).

The control channel for the group assignment segment is a multicastassignment message and is located within the resources allocated for thegroup assignment segment.

To identify the group assignment segment, the group assignment messageis scrambled by the group ID.

The message length is known to all the mobiles in the group.

FIG. 21 shows an example of a group assignment segment.

UL Control Segment

Multiple users are assigned resources using an UL CI. This is thenfollowed by unicast assignment information for each user.

The unicast information is a fixed length and is decoded by each usersequentially until the mobile finds its UL unicast assignment message.

The unicast information contains the assigned MCS and it is scrambled bythe user ID of the intended user.

The group UL assignment messages are signaled after the unicast ULassignments. The group assignment message length is an integer multipleof the unicast message and it is scrambled by the group ID (see VoIPcontribution C80216m-08_177 also in other appendices).

FIG. 22 shows an example of an uplink control segment.

Retransmission Segment

The retransmission segment is only required when resource adaptivesynchronous HARQ is used.

In resource adaptive synchronous HARQ, the retransmissions occur at apre-determined time and at the same MCS as the original transmission.

Only the resource location is adapted.

The retransmission segment is partitioned using a combination index,which is signaled at the beginning of the retransmission segment.

The retransmission combination index is scrambled by a unique code thatidentifies the retransmission segment.

The retransmission CI is then followed by a unicast message for eachretransmission. The unicast message consists of the resource ID of thetransmission on the previous interlace.

FIG. 23 shows an example of a retransmission segment.

Persistent Resource Assignment

Persistent resource assignment can be used for low geometry users fortraffic such as VoIP.

Persistent sub-zone allows multiplexing of persistent resource andnon-persistent assignments through the RAB.

Details of the persistent sub-zone and RAB are given in the VoIPcontribution C80216m-08_177.

Resource Allocation within a Localized Zone

A localized zone can use either dedicated pilots or common pilots (seecontribution C80216m-08_172 included in other appendices). Dedicatedpilots can be used when preceding is performed.

In both cases, a PI is used to indicate how the sub-bands are allocatedto different users.

The multicast control segment containing the PI is sent in a diversityzone. Other multicast and broadcast messages that require frequencydiversity are sent on the diversity zone.

The user specific resource assignment is signaled within the resourcesallocated to the user.

-   -   This improves the control channel robustness, since the control        channel will be located in the mobile's best sub-band.    -   In the case where dedicated pilots are used for beamforming, the        control channel is also preceded using the same preferred        preceding vector as for the data, which further improves the        control channel.    -   The MCS and power allocated for the control can be different        than the data.

Control Channel Overhead Comparison

The overhead for the proposed control channel is compared with the WiMAXreference system and with UMB for two cases.

-   -   Case 1: Simple non-MIMO assignments (e.g. STTD R1/R2).    -   Case 2: Single user MCW MIMO assignment with 4 layers.

Only overhead due to resource allocation is included. Other controloverhead such as DL ACK channel and power control channel are notincluded in the overhead calculations.

Assumptions for WiMAX Reference System Overhead Calculations:

-   -   FCH is modeled.    -   The map is transmitted using QPSK 1/2, with repetition =6. Three        sub-maps are transmitted using QPSK 1/2 with repetition=4, 2,        and 1.    -   The user distributions for the MAP and the 3 sub-maps is 0.07,        0.20, 28, 0.45, respectively.

Assumptions for UMB Overhead Calculations:

-   -   The unicast messages in the F-SCCH are 39 bits long (including        CRC).    -   One F-SCCH message is needed for each assignment in case 1.    -   Two F-SCCH messages are needed for each assignment in case 2.    -   The F-SCCH is transmitted using QPSK 1/3.

Control Channel Overhead Comparison Assumptions for Nortel OverheadCalculations:

-   -   The multicast control segment consists of a 10 bit combination        index and a CRC of 6 bits.    -   The non-MIMO assignments in case 1 are 22 bits including CRC.    -   The MIMO assignments in case 2 are 38 bits including CRC.    -   The Multicast control segment is transmitted using QPSK 1/3 with        repetition =2 and the unicast messages are transmitted using        QPSK 1/3.    -   There are 24 BCUs in a 10 MHz. One BCU is used to transmit the        CI and DL ACK channel and other DL control channels. There are        23 available BCUs for DL assignments.

Control Channel Overhead Comparison

FIGS. 24 and 25 are Tables for control channel overhead comparison.

Comparison of Blind Decoding Complexity

In LTE, the number of blind decoding attempts as provided incontribution R1-081101:

-   -   For common search space is ˜10;    -   For UE specific search space is ˜30;    -   The total is ˜40 blind decoding attempts every TTI, which is        equivalent to 2 Mbps.

The Number of Blind Decoding Attempts in the Nortel Proposal:

-   -   Up to 2 attempts for different unicast message types per        partition;    -   Since the expected number of partitions <10, the total number of        blind decoding attempts <20<LTE.

Summary

In summary, the proposed control channel design shows a significantimprovement in control overhead over both the WiMAX reference system aswell as UMB.

The new design minimizes both power and bandwidth overhead.

The lower overhead is attributed to following.

-   (A) Using a combination index rather than a channelization tree.    -   More flexibility (no restrictions in the number of resources        that can be assigned).    -   Lower overhead since the node ID does not have to be signaled in        each assignment.-   (B) Taking advantage of multicast control and unicast control.    -   Multicast control is used to signal common information that is        needed by all the assigned users.    -   Unicast control is used to signal user specific information.-   (C) By combining the unicast control with the data, the resource    granularity for the control is lower.    -   For unicast control, the granularity is to the unit of a single        tone.    -   For group control, the granularity is to the unit of RBs.

This new design also allows for micro-sleep to be enabled by orderingthe tones in frequency first and then assigning tones to the controlchannel at the beginning of the allocated resources.

APPENDIX C: PROPOSAL FOR IEEE 802.16M DL RESOURCE BLOCKS ANDCHANNELIZATION

Document Number: IEEE C802.16m-08/175.

Date Submitted: 2008 Mar. 10.

Source: Sophie Vrzic, Mo-Han Pong, Robert Novak, Jun Yuan,

Dongsheng Yu, Anna Tee, Sang-Youb Kim, Kathiravetpillai Sivanesan.

Nortel Networks.

Re: IEEE 802.16m-08/005-Call for Contributions on Project 802.16m SystemDescription Document (SDD), on the topic of “Downlink Physical ResourceAllocation Unit (Resource Blocks and Symbol Structure)”.

Purpose: Adopt the proposal into the IEEE 802.16m System DescriptionDocument.

Scope

This contribution proposes a new resource block structure andchannelization for IEEE 802.16m.

The pilot design and resource allocation and control are presented inseparate contributions (see C802.16m-08_172 and C802.16m-08_176 alsoincluded in other appendices).

Motivation

The legacy 16e system uses a TDM approach to configuring diversity,localized and MIMO zones.

In an FDM approach, the channelization can span across all symbols in asub-frame. Different zones are configured to use a different portion ofthe band. Spanning the channelization across all symbols allows forefficient power control of both control and traffic.

Overview of Channelization Design

New channelization and control channel design are defined for IEEE802.16m sub-frames.

The channelization for control and traffic is confined within eachsub-frame and span across all the symbols within the sub-frame.

Extended sub-frames can be defined to concatenate the sub-channelresources across multiple sub-frames to reduce control overhead andimprove UL coverage. This is for FFS.

Within a 16 m sub-frame, the bandwidth is divided into one or morezones. Each zone consists of a set of physical tones. The set ofphysical tones that belong to a zone may be either contiguous ornon-contiguous.

The zones are used for:

-   -   Diversity channel assignments;    -   Frequency selective scheduling (localized zone);    -   Fractional frequency reuse (FFR);    -   Single Frequency Network (SFN) transmission.

The hopping pattern is always confined within a zone.

-   -   For SFN transmission, the hopping pattern is the same in the        corresponding zones in sectors that are involved in the SFN        transmission.    -   For FFR the hopping pattern is different for different sectors.

Each zone has a one-dimensional ordered list of resources, in units ofBasic Channel Units (BCU).

Basic Channel Unit (BCU):

-   -   A BCU consists of 3 resource blocks (RB), where a RB is 12 tones        and 6 OFDM symbols. The details of the RB definition and the        pilot design are described in a separate contribution (see        C80216m-08_172).    -   For a 10 MHz system, there are 24 BCUs.    -   In the localized zone, a BCU is formed from contiguous physical        tones.    -   In the diversity zone, a BCU is formed from physical tones that        are spread over the entire zone.    -   Each BCU spans over all OFDM symbols in a sub-frame.    -   The partitioning of resources between the localized and        diversity zone is in units of BCUs.

Defining a BCU size of 3 RBs has the following advantages.

-   -   This BCU size is an adequate size for proper channel estimation        using common pilots.    -   This RB size provides enough granularity and flexibility for        VoIP assignments (see C802.16m-08_177).    -   For group assignments, such as VoIP, groups are allocated in        units of BCUs, whereas individual VoIP users can be allocated        resources in units of RBs.    -   For non-VoIP assignments, the resource unit does not have to be        as granular.

The resources are assigned using a combination of a multicast messageand separate unicast messages for each assignment. The details of thecontrol channel are described in a separate contribution (see controlchannel contribution C80216m-08_176).

FIG. 26 shows a Mapping of Physical to Logical Resources for a DiversityZone. Each RB consists of tones that are evenly spread over the entirebandwidth. The tones from two adjacent logical RBs are defined so thatthe distance between tones is maximized.

Channelization Procedure

Step 1: The sub-carriers in a band are partitioned between localizedzone and diversity zone in units of physical BCUs, i.e. 36 tones. Thephysical tones in the band are assigned to each zone by first assigningcontiguous tones, in units of BCUs, for the localized zones and evenlydistributing the remaining tones for distributed zones. The assignmentof physical tones to each zone can hop from time to time, e.g. symbol tosymbol or set of symbols to symbols, frame by frame etc.

Step 2: Once the zones are formed by a set of physical tones, thephysical tones are permuted with a sector and zone specific permutationto map to logical tones.

Step 3: An ordered list of RBs is then formed for each zone where eachRB consists of a set of logical tones. BCUs are formed by grouping 3RBs.

FIG. 27 shows one embodiment of the channelization procedure.

-   -   Step 1 (S1): physical tones are assigned to zones;    -   Step 2 (S2): logical tones of each zone are formed by        permutation;    -   Step 3 (S3): BCUs are formed from logical tones of each zone.

Channelization Procedure (Alternative)

In a band, if the diversity zone is a size of one or two BCUs, then theRBs used to form the BCU s can be distributed across the band. Thisimproves the diversity order of the logical BCUs.

To improve channel estimation in each of the disjoint diversity RBs, ahigh density pilot pattern should be used in these RBs.

See FIG. 28, which illustrates an embodiment of the alternativechannelization procedure.

Zone Configuration

FIG. 29 illustrates how the different zones can be configured in onesub-frame.

A separate control channel is contained within each zone.

The control channel spans all OFDM symbols.

The FFR zones can be either diversity or localized zones.

See FIG. 29, which illustrates an example of power vs. logical frequency(BCU) for each of three sectors.

Channelization for Multi-Carrier

In multi-carrier operation there are two options.

In option 1, each carrier can have a different channelization dependingon number of zones that are configured. In this case, each carrier willhave a separate control channel.

In option 2, the channelization can span multiple bands.

-   -   This case is used for transmissions to wide band users.    -   In this case, a single control channel can be used.

FIG. 30A illustrates the option where each carrier has a separatecontrol channel.

FIG. 30B illustrates the option where a single control channel is usedfor multiple bands.

APPENDIX D: PROPOSAL FOR IEEE 802.16M VOIP CONTROL CHANNEL

Document Number: IEEE S802.16m-08/xxx.

Date Submitted: 2008 Mar. 17.

Source: Robert Novak, Mo-Han Pong, Sophie Vrzic, Dongsheng Yu, Jun Yuan,Anna Tee, Sang-Youb Kim.

Nortel Networks.

Venue: Orlando, US.

Base Contribution: IEEE C802.16m-08/xxx.

Purpose: Adopt the proposal into the IEEE 802.16m System DescriptionDocument.

Scope

This contribution presents control channel signaling design for thesupport of real-time services such as VoIP for IEEE 802.16m.

This contribution can be used in conjunction with the control channelsignaling design (Control contribution) to form the complete 802.16mcontrol channel design.

Introduction

Real-time service support is an essentially feature of 16m systems. Suchservices may include: VoIP; Gaming; Video telephony.

These services are characterized by delay sensitive data requirements,small throughputs, and relatively high number of users.

The SRD requirements necessitate efficient control channel signalingdesign with capability of accommodating high numbers of users.

-   -   Efficient multiplexing of users on the UL and DL is necessary to        ensure high capacity for such services.    -   16m VoIP SRD requirements: 1.5x reference system capacity; 30        users/MHz/sector.

Control channel design for real-time service can be different than thoseuse for packet data, but must be able to be used simultaneously in orderto support mixed traffic scenarios.

Background

Due to the relatively larger number of simultaneous VoIP users, it isimperative that the 16m control channel structure for VoIP be designedsuch that the overhead per HARQ transmission assignment must remain onthe order of a few bits. In addition, many transmission parameters suchas packet and modulation schemes may be common to all VoIP users andtherefore do not need to be signaled.

Explicit signaling with conventional unicast control signaling used fordata packet transmissions, while generally power efficient, can beprohibitive due to larger overhead associated with additionaltransmission parameters not necessary for VoIP.

Broadcast methods can eliminate many of these common fields but sufferfrom inefficient transmission to both cell edge and high geometry usersimultaneously.

Current methods in 802.16e do not have specific signaling support forVoIP, and as a results the signaling overhead is large. This allows formaximum flexibility and specification of VoIP packet allocation, howeverit is capacity limiting. This is due to the large broadcast fixedoverhead, as well as the considerable signaling overhead per HARQtransmissions.

-   -   The legacy 16e system can use sub-MAPS to target several        geometry groups separately, however the overhead limitation        exists even with the use of sub-MAPS. FIG. 31 illustrates the        use of sub-maps in a legacy 802.16e system.    -   For a 1x2 IEEE 802.16e system, the DL overhead with 140 users        per link, and 10% re-transmission rate:    -   MAP overhead corresponds to 230 slots (64%); and    -   Using 3 sub-maps corresponds to 144 slots (40%).

Multi-cast methods, such group signaling methods as specified for 3GPP2UMB systems, are useful in that the number of bits per assignment isrelative small, while the use of multiple groups allow targeting ofdifferent of geometries to improve power efficiency. Efficientmultiplexing of group resources is needed to maintain this powerefficiency.

In some cases, assignment modifiers may be desirable to enhance systemfeatures or reduce hypotheses in blind detection of a transmission. Suchmodifiers can be useful for group allocations however in many cases, thenumber of assignments for a group is unknown prior to bitmap receptionand ultimately require significant bit-padding in order to make use ofthese fields.

Proposal

This contribution proposes a group-based control channel framework forVoIP and real-time services. The proposal combines the efficiency andflexibility of unicast assignment by maintaining small groups and addingassignment modifiers, as well reduces control overhead and messages byusing group-based assignment.

The group signaling methods can be integrated with a dynamic resourcepartition framework [Control Channel contribution] to provide efficientmultiplexing of different multi-cast groups, and well as data packettraffic. Assignment modifiers can also be added to group signaling withminimum field padding in this proposal.

Proposal for 16m

Group-based assignment (bitmap).

-   -   Allow efficiently signaling to many VoIP users simultaneously.    -   Signaling only non-persistent assignments/transmissions.    -   Assignment modifier to allow addition specification of        transmission.

Persistent Allocation.

-   -   Predefined resource for certain VoIP transmissions or        assignments to reduce signaling.    -   Occupied resource indicated by resource availability bitmap        (RAB).

Multiplexing of group resources achieved by resource partitioning.

-   -   Flexible group resource assignment size and multiplexing by        signaling partition sizes.    -   Hypothesis detection of group bitmaps allows flexibility in        group partition location.

Non-Persistent Group Assignment

Group assignment is used to benefit large number of users.

-   -   A group is signaled by a group bitmap.    -   Each location in the bitmap is assigned to a user. The value of        the bit for each user indicates whether the user is being        assigned resources ('1′), or not being assigned resources ('0′).    -   The first indicated assignment is assigned to the first        available resource(s), the second indicated assignment is        assigned to the second available resource(s).    -   See FIG. 32, which gives an example of a group assignment        bitmap.    -   Each group bitmap has its own set of resources (i.e. different        resource segment).

Improve flexibility by hypothesis detection of group bitmaps.

-   -   For DL assignments, a user will try to decode the start of each        resource segment with its group ID attempting to find its group        resource assignment.    -   For UL assignments, a user will try to decode each possible        position for a control message in the UL assignment control        segment with its group ID attempting to find its group resource        assignment.    -   Allows bitmaps to be sent as needed on a 16m mini-slot and on        different resource location.

Easy multiplexing of group resource facilitates the use of many groups.

-   (1) Groups based of service class. Some services require frequent    transmission (VoIP), others less frequent.-   (2) Groups based on geometry. Power efficiency.-   (3) To reduce signaling, groups may also have the same attributes    (useful for VoIP): MIMO mode; Resource allocation size; and MCS.-   (4) A specific group assignment bitmap may be omitted if no users of    that group require assignment.

Users are assigned to groups by group configuration message. Messageindicates size of bitmap, bitfields to be included, and attributes.

Supporting Features for Group Assignments

Assignment Related Fields:

-   -   Each field is linked to number of indicated assignments of the        bitmap, which can be derived from the partition size.    -   Hence each user can determine the field/index sizes dynamically.

(1) Supplemental Transmission Information Field (STIF): Up to 2 bits toindicate new packet transmissions, multiple packets or packet startposition.

(2) Resource permutation index: Index linked to table of possibleresource allocations sizes to indicated assignment in bitmaps.

-   Allows dynamic resource size for bitmaps allocations.

(3) Users set index: Index that shuffles indicated assignments. Can beto create “pairs” or sets of users. Can be used to assigned specificresources to specific users. Can be used in MIMO applications.

Group Related Field: UL resource/partition index.

-   Indicates the resource partition assigned to the group bitmap.-   Multiple groups can be assigned to the same partition.

Supplemental Transmission Information Field (STIF)

(1) Indicates one (or more) of:

(a) new packet toggle (NPT) (multi-state toggle), which preventsambiguity of transmission to user in case of ACKJNAK error as it changesvalues each time a new packet is started;

(b) multiple packets (MP), which allows BS to specify that 2 packets arebeing transmitted to a user, also indicates to other users of the groupthat this assignment will uses twice the resources;

(c) packet start frame (PSF) within superframe, which indicates theframe within the superframe on which the first HARQ packet transmissionoccurred. This indication simplifies hypothesis detection in thepresence of control signaling errors;

(d) Subpacket HARQ transmission index (SPID), which indicates thesubpacket ID in for HARQ transmissions. Enables asynchronous IR HARQpacket transmissions.

(2) The mode is configured for each group bitmap. Can also be configuredas one-bit field (2 state) for 1 mode, or 2-bit field (4 state) whichcan be configured to support one or more of the above modes.

See FIG. 33 illustrates an example of the assignment bitmap and thesupplemental transmission information field (STIF).

Resource Permutation Index

This field may be present and may be used to assign different numbers ofresources to users of a given group.

-   -   For a particular number of resources within the group assignment        segment, a table can be created to indicate possible resource        partitions to different users within the group.    -   This field signals the index associated with resource partitions        of the group assignment.    -   For example, for the case of a partition size of 4 resources, a        table can be created linking possible with an index. If the        group is configured to use this filed, by noting the partition        size and the minimum resource division size, the user can        determine that a 3-bit field is appended to the bitmap. Hence        the size of the index is dynamically flexible, and is associated        with the partition size

See FIG. 34, which is a table illustrating an example of partitiondivisions, corresponding index numbers and corresponding bitfields.

Users Sets Index;

Reordering, or Creating Users Sets within Bitmap

The field indicates an index that corresponds to combinations of pairsor sets of assigned users.

-   Users with indicated assignments are combined into pairs, triples,    quadruples, etc. . . . .-   This allows selected multiple users to be assigned to the same    resource.-   Without this index the users are paired in the order of bitmap    positions.

For a number of indicated assignments, a table can be created ofpossible pairs or sets of users.

Example:

-   -   The bitfield “01”, indicates that assignment 1 and 3 are paired        on the first resource, and assignment 2 and 4 are paired on the        second resource.    -   Hence, UE12 and UE46 are paired on the first resource, and UE30        and UE24 and paired on the second resource.

FIG. 35 illustrates an example of the assignment bitmap and the pairingor sets combination index. FIG. 36 is a table showing an example of usercombinations, corresponding index numbers and corresponding bitfields.

UL Resource/Partition Index: Bitfield on UL Control Message that Pointsto Resources

Assignment group bitmap messages are appended by a bit field specifyingthe UL partition number for the assignment.

Multiple bitmaps can be assigned to the same partition. Multiple groupscan be assigned to the same partition to support collaborative spatialmultiplexing (CSM).

Group assignments with indicated assigned resources greater than thepartition size, start from the end of the partition and allocateresource across to the partition to the beginning, and then continuestarting again from the end of the partition.

-   -   Mobiles can derive total number of assigned resources to group        from bitmap, and compare with indicated resource partition size.    -   Method allows efficient packing of different sized group        assignments.

Users ordering index can also be used to allocate users in a specificorder.

-   -   For a number of indicated assignments, a table can be created of        possible ordering of users.    -   User ordering index may also be used to “shuffle” the        assignments of one or more group bitmaps to allow further        control over which users are grouped together for optimization.    -   Index to be appended to high geometry bitmap to minimize        overhead. In order to allow derivation of field size, index        applies to only one CSM layer.    -   Ordering index is a specific case of user set index, with user        set size equal to 1.

FIG. 37 is a User Ordering Index Table showing assignment orderingexamples, corresponding index numbers and corresponding index bitfields.

FIG. 38 gives an example of the multiplexing of unequal assignments.Group 1 corresponds to 6 assigned resources. Group 2 corresponds to 10assigned resources. The partition corresponds to 8 resources.

Persistent Resource Assignment

Persistent resource assignment can be used for low geometry users.

-   -   Persistent assignment does not require control signal after        initial configuration.    -   All HARQ transmissions are sent on periodically occurring        persistent assignment.    -   FIG. 39 illustrates an example of persistent resource        assignment.

Persistent sub-zone allows multiplexing of persistent resource andnon-persistent assignments. A resource availability bitmap is employedto indicate which specific resources are available within the partitionwithin the persistent sub-zone.

Persistent assignment for first HARQ transmission, or re-transmissionsis also supported. Persistent resources for first HARQ transmissions areconfigured at initial assignment, and re-transmissions are signalednon-persistently by group assignment.

Assigned/deassigned by unicast control message.

Overview of VoIP Control Channel within Resource Partition Framework

VoIP transmissions can be persistent assignments, or non-persistentassignments signaled within specific resource partitions.

-   -   Group assignment using a bitmap is used for non-persistent VoIP        assignments. Each group is assigned a separate resource        partition.    -   Persistent assignments are indicated to other users by resource        availability bitmap (RAB).

Division and identification of available resources is indicated by themulticast control segment (MCCS). Partition of zones is signaled bycombination index (CI) which signals the resource partitions within thepersistent and non-persistent zones.

The CI is concatenated and encoded with a resource availability bitmap(RAB) which indicates the available resources in the persistentsub-zone. The RAB is a bitmap that indicates which resources areavailable, and which are occupied with a persistent HARQ transmission.Persistent resources that are unused due to packet arrival Jitter,silence state, or early termination of HARQ transmissions are shown asavailable.

The resource partitions indicated by the CI divide the set of resourcesremaining after resources indicated as occupied by the RAB are removedfrom the resource list. The size of the persistent zone is carried inthe secondary broadcast channel.

FIG. 40 illustrates an example of a multicast control segment (MCCS)including a combination index (CI) and a resource availability bitmap(RAB).

Resources Map—DL+UL Assignments

See FIG. 41, which illustrates an example of a combination index (CI)including group assignment messages (denoted G₁, G₂, G₃), an uplinkcontrol segment (UL CS) and unicast assignment messages (denoted U₂ andU₃). Also, an example of a group assignment message (see G₂) is given.In FIG. 41, the following notations are used:

-   -   MCCS=Multicast Control segment;    -   CI=Combination Index;    -   RAB=Resource availability bitmap;    -   UCTS=Unicast control and traffic segment;    -   U=Unicast assignment message;    -   GCTS=Group control and traffic segment;    -   G=Group assignment message;

-   UL CS=Uplink Control segment.

The available resources for each group assignment are indicated byseparate resource partitions per mini-frame.

-   Resources for different groups are dynamically multiplexed.-   A resource availability bitmap (RAB) may also be employed indicate    which specific resources are available within the partition.

Resources Map—UL Control Segment

FIG. 42 illustrates an example of resources map—uplink control segment.U₁, U₂ and U₃ are unicast assignment messages. G₁, G₂, G₃ and G4 aregroup assignment messages. In FIG. 42, the following notations are used:

-   -   CI=Combination Index;    -   RAB=Resource availability bitmap;    -   U=Unicast assignment message;    -   G=Group assignment message.

UL Assignment block is located in a DL resource partition. Partitioncontains CI, RAB, and unicast/group assignments.

Combination index indicates the resource partitions on the Uplink.

-   -   RAB indicates resources “in use” by persistent assignments, and        resources available.    -   Resource partitions specified in CI excluded resources indicated        as “in use” by the RAB.

For group assignment messages (and unicast):

-   -   Assignment messages are appended by a bit field specifying the        UL partition number for the assignment.    -   Multiple groups can be assigned to the same partition to support        collaborative spatial multiplexing (CSM).    -   Unicast messages precede group messages in order to facilitate        ACK/NAK operation.    -   Group message length is set to be multiple of unicast length.

VoIP Packet Sizes

Resource block size 72 (12×6) bits as discussed in pilot/RB contributionprovides flexibility in code rate for assignment. This RB size can beassigned in units of 3 RB's.

Downlink (DL):

-   (A) 2 transmit antennas →6% pilot overhead.-   (B) 320 bit VoIP packet size (AMR full rate). 2 Options for resource    size for QPSK:    -   3 RB=1st transmission code rate 0.788; and    -   4 RB=1st transmission code rate 0.59.-   (C) 256 bit VoIP packet size (EVRC full rate). 2 Options for    resource size for QPSK:    -   2 RB=1st transmission code rate 0.95;    -   3 RB=1st transmission code rate 0.63.

Uplink (UL):

-   (A) 2 transmit antennas →12% pilot overhead.-   (B) 320 bit VoIP packet size (AMR full rate). 2 Options for resource    size for QPSK:    -   3 RB=1st transmission code rate 0.84;    -   4 RB=1st transmission code rate 0.63.-   (C) 256 bit VoIP packet size (EVRC full rate). 2 Options for    resource size for QPSK:    -   3 RB=1st transmission code rate 0.67.

For both UL and DL, small RB size allows for multiple reliabilityoptions with QPSK, and allows for adaptation to pilot/codecrequirements.

Majority of coding gain achieved after 2^(nd) IR transmission.

Assignment Overhead Comparison (including CI)

Total Overhead for UL+DL resources (48.6 OFDM symbols) in TDD frame(1:1) partition.

Estimates assume full power transmission such that BW overhead isapproximately equal to power overhead.

-   -   MCS, QPSK rate 1/2, with repetitions 1, 2, 4 and 6 for all        schemes (WiMAX turbo encoder curves);    -   Overhead does not included any padding; or    -   12×6 RB size, 3 RB's per assignment.

UL overhead assumed to be same as DL overhead.

16m Group Assignment Entries Assume:

-   (1) User divided into 16 bitmaps.    -   4 interlace based bitmaps, each with 14 geometry based bitmaps.    -   Lowest level maybe persistently assigned.-   (2) New packet assignment modifier bit (2 bit per indicated    assignment).    -   Transmission opportunities every 5 ms.    -   Without modifier, start frames are limited by increased        hypothesis detection.-   (3) 10-bit for CI:    -   Persistent encoded with RAB and 16-bit CRC.    -   Non-persistent encoded with 8-bit CRC.

UMB Group assignment entries assume:

-   (1) 1 geometry level for bitmap, RAB attached to lowest geometry    level bitmap.-   (2) Users from a geometry level divided into 8 bitmaps.    -   4 interlace based bitmaps, each with 2 start frames per 20 ms        superframe.    -   Allows packet start every 10 ms.

FIG. 43 is a table illustrating an assignment overhead comparison fordifferent numbers of users.

APPENDIX E: PROPOSAL FOR IEEE 802.16M RESOURCE ALLOCATION AND CONTROLFOR MULTI-CARRIER OPERATION

Document Number: IEEE C802.16m-08/178.

Date Submitted: 2008 Mar. 10.

Source: Sophie Vrzic, Mo-Han Fong, Robert Novak, Jun Yuan,

Dongsheng Yu, Anna Tee, Sang-Youb Kim, Kathiravetpillai Sivanesan.

Nortel Networks.

Re: IEEE 802.16m-08/005-Call for Contributions on Project 802.16m SystemDescription Document (SDD), on the topic of “Downlink ControlStructures”.

Purpose: Adopt the proposal into the IEEE 802.16m System DescriptionDocument.

Scope

This contribution presents the IEEE 802.16m resource allocation andcontrol design for multi -carrier operation.

The resource allocation and control design for single carrier ispresented in contribution C802.16m-08_176.

Overview

In multi -carrier operation, each carrier has its own control channel.

A mobile may be assigned one or more primary carriers for decoding thescheduling control information (see contribution on Resource Allocationand Control for Multi-Carrier C802.16m-08_178).

The mobile reads the multicast control segment in its primary carrierand then searches each partition to find its unicast assignment (seecontribution on Resource Allocation and Control C802.16m-08_176).

The unicast assignment indicates whether or not the data is contained onthis primary carrier or another carrier.

If data is contained on another carrier then the carrier and thepartition number are indicated in the unicast assignment message on theprimary carrier.

Data can be contained within the assigned partition of the primarycarrier as well as the indicated carrier.

Multi-Carrier Control

In the example below, the mobile is assigned carrier 1 as its primarycarrier.

The mobile reads the combination index on the primary carrier and usingblind detection it decodes the unicast message in the second partition.

This unicast message indicates that the data is contained in the thirdpartition of carrier 2.

The mobile must then decode the CI of carrier 2 to determine thelocation of the third partition.

FIG. 44 shows a unicast message on Carrier 1, where the unicast messageindicates that data in contained in a third partition on Carrier 2.

The Advantages of Assigning Secondary Carriers are:

-   -   System information does not have to be broadcast on secondary        carriers;    -   A preamble is not required on secondary carriers; and    -   Introducing secondary carriers leads to reduced overhead since        the same information does not have to be transmitted on multiple        carriers.

When there is an active traffic transmission, the MS has to sendACK/NACK on the same carrier as the traffic was sent/received.

Asynchronous retransmissions do not have to be transmitted on the samecarrier. Retransmissions are signaled on the primary carrier, but can bescheduled on either the primary or secondary carriers.

For resource adaptive synchronous HARQ, there are three options formulti-carrier control.

Option 1: Resource adaptive synchronous retransmission is on the samecarrier as original transmission (the MS has to monitor the secondarycarrier and its own primary carrier).

-   (a) MS needs to do blind decoding for new packet (e.g. 3 message    lengths) of all segments on the primary carrier.-   (b) MS needs to do blind decoding for retransmission packet (1    message length) of all segments on the secondary carrier.

Option 2: Resource adaptive synchronous retransmission on the primarycarrier (original transmission on another carrier).

-   (a) Need to signal the original carrier ID (3 bits) and the resource    ID in the original carrier (5 bits).-   (b) MS needs to do blind decoding of both new packet and    retransmission packet (total 4 message length) of all segments on    primary carrier.

Option 3: Resource adaptive sync retransmission on any other carriers.

-   (a) Need to signal the original carrier ID (3 bits), the resource ID    in the original carrier (5 bits), the destination carrier ID (3    bits) and the resource ID in the destination carrier (5 bits).-   (b) MS needs to do blind decoding of both new packet and    retransmission packet (total 4 message length) of all segments in    primary carrier.

All options have the same number of blind decoding attempts.

-   Option 1 has the least overhead but least flexibility.-   Option 3 has the most overhead and is most flexible. But option 3    can be achieved by asynchronous retransmission, which has more    flexibility.

Conclusion is to use Option 1 for resource adaptive synchronous HARQbecause:

-   (a) Option 2 is not flexible to adapt the CQI of different carriers.-   (b) Load balancing is a long term operation. The assigned carrier    does not need to change dynamically.

The CQI feedback should be per carrier to keep the design systematic:

-   (a) The carrier used for CQI measurement and feedback is configured    by the BS.-   (b) The MS monitors the superframe configuration control information    on the primary and secondary carriers.-   (c) Primary carriers are for mobiles that are not in active traffic    transmission and don't need to feedback information, e.g. in sleep    mode and idle mode.

In summary, the notion of primary/secondary is useful:

-   (a) Save overhead of broadcasting system information on the    secondary carrier.-   (b) Save the number of blind detection attempts required.

The MS only monitors the frame control from one carrier. This reducesthe number of control packets to decode or blind detections.

Those skilled in the art will recognize improvements and modificationsto the embodiments of the present invention. All such improvements andmodifications are considered within the scope of the concepts disclosedherein and the claims that follow.

What is claimed is:
 1. A base station serving a network, the basestation comprising: a receiver, transmitter and baseband processor forfacilitating wireless communications with mobile stations; and a controlsystem associated with the receiver, transmitter and baseband processorand adapted to: detect an event indicating that a first of the mobilestations is initiating a random access procedure; and in response todetecting the event, start broadcasting essential physical layerconfiguration information, wherein the essential physical layerconfiguration information is usable by mobile stations in range of thebase station to facilitate communications with the base station, whereinthe essential physical layer configuration information is not broadcastprior to detecting the event.
 2. The base station of claim 1, whereinthe essential physical layer configuration information comprisesmulti-carrier configuration information.
 3. The base station of claim 1,wherein the multi-carrier configuration information identifies a primarycarrier and one or more secondary carriers.
 4. The base station of claim1, wherein the essential physical layer configuration informationfurther comprises at least one of bandwidth configuration informationand time division duplex (TDD) ratio.
 5. The base station of claim 1,wherein the essential physical layer configuration information is usableby the first mobile station for decoding physical layer informationtransmitted by the base station.
 6. The base station of claim 5, whereinthe control system is further adapted to: after the first mobile stationhas performed initial system access for network entry, transmit to thefirst mobile station additional control information that provides mediaaccess control or other upper layer configuration information.
 7. Thebase station of claim 6, wherein said transmitting the additionalcontrol information comprises unicasting the additional controlinformation to the first mobile station.
 8. The base station of claim 1,wherein the control system is further adapted to: detect a second eventindicating that the first of the mobile stations is performing a furtherrandom access procedure.
 9. The base station of claim 1, wherein saidinitiating the random access procedure is part of an initial systemaccess procedure.
 10. The base station of claim 1, wherein the basestation and the first of the mobile stations support multicarrieroperation, and the first of the mobile stations is instructed by thebase station to monitor a subset of the carriers for controlinformation.
 11. A method for operating a base station serving anetwork, the method comprising: detecting an event indicating that afirst of the mobile stations is initiating a random access procedure;and in response to detecting the event, starting to broadcast essentialphysical layer configuration information, wherein the essential physicallayer configuration information is usable by mobile stations in range ofthe base station to facilitate communications with the base station,wherein the essential physical layer configuration information is notbroadcast prior to detecting the event.
 12. The method of claim 11,wherein the essential physical layer configuration information comprisesmulti-carrier configuration information.
 13. The method of claim 11,wherein the essential physical layer configuration information is usableby the first mobile station for decoding physical layer informationtransmitted by the base station.
 14. The method of claim 13, furthercomprising: after the first mobile station has performed initial systemaccess for network entry, transmitting to the first mobile stationadditional control information that provides media access control orother upper layer configuration information.
 15. The method of claim 11,wherein the base station and the first of the mobile stations supportmulticarrier operation, the method further comprising: instructing thefirst of the mobile stations to monitor a subset of the carriers forcontrol information.
 16. An apparatus comprising: memory storing programinstructions; one or more processors, wherein the program instructions,when executed by the one or more processors, cause the one or moreprocessors to: monitor at least one sub-frame location to receive afirst message from the base station, wherein the first message includesan alert flag for both of active and idle modes of operation of theapparatus; receive the alert flag, wherein the alert flag is set to afirst state indicating that the second control information is differentfrom first control information that is currently in effect, wherein thesecond control information is to take effect in the future; receive aversion number that corresponds to the second control information,wherein the version number represents a count of control informationchanges; in response to determining that the alert flag is set to thefirst state, determine whether the version number corresponding to thesecond control information is different than a version of controlinformation that has been previously decoded and stored based; and inresponse to determining the version number corresponding to the secondcontrol information is different than a version of the controlinformation that has not been previously decoded and stored, decode andstore the second control information.
 17. The apparatus of claim 16,wherein the version number and is transmitted in a frequent and periodicmanner.
 18. The apparatus of claim 16, wherein the apparatus isconfigured to support orthogonal frequency division multiplexing (OFDM)communications.
 19. The apparatus of claim 16, wherein the alert flaghas only two states.
 20. The apparatus of claim 16, wherein the programinstructions, when executed by the one or more processors, cause the oneor more processors to: receive an action time indication in associationwith reception of the second control information, wherein the actiontime indication is indicative of when the apparatus should start usingthe second control information.